diff --git a/src/parallel/decompose/decompose/Make/files b/src/parallel/decompose/decompose/Make/files
index 47689307fa..4435b3cb4f 100644
--- a/src/parallel/decompose/decompose/Make/files
+++ b/src/parallel/decompose/decompose/Make/files
@@ -1,15 +1,15 @@
-decompositionInformation.C
-decompositionModel.C
+decompositionInformation.cxx
+decompositionModel.cxx
 
-dimFieldDecomposer.C
+dimFieldDecomposer.cxx
 
-fvFieldDecomposer.C
-fvFieldDecomposerCache.C
+fvFieldDecomposer.cxx
+fvFieldDecomposerCache.cxx
 
-pointFieldDecomposer.C
-pointFieldDecomposerCache.C
+pointFieldDecomposer.cxx
+pointFieldDecomposerCache.cxx
 
-lagrangianFieldDecomposer.C
-lagrangianFieldDecomposerCache.C
+lagrangianFieldDecomposer.cxx
+lagrangianFieldDecomposerCache.cxx
 
 LIB = $(FOAM_LIBBIN)/libdecompose
diff --git a/src/parallel/decompose/decompose/decompositionInformation.C b/src/parallel/decompose/decompose/decompositionInformation.cxx
similarity index 97%
rename from src/parallel/decompose/decompose/decompositionInformation.C
rename to src/parallel/decompose/decompose/decompositionInformation.cxx
index 8b4a31b7b4..1a52035e55 100644
--- a/src/parallel/decompose/decompose/decompositionInformation.C
+++ b/src/parallel/decompose/decompose/decompositionInformation.cxx
@@ -55,7 +55,7 @@ void Foam::decompositionInformation::populate
     {
         const label ownProc = decomp[celli];
 
-        labelList& subdist = distrib_[ownProc];
+        labelUList& subdist = distrib_[ownProc];
 
         // Number of cells
         ++subdist[ownProc];
@@ -80,7 +80,7 @@ void Foam::decompositionInformation::populate
 
     forAll(distrib_, ownProc)
     {
-        const labelList& subdist = distrib_[ownProc];
+        const labelUList& subdist = distrib_[ownProc];
 
         cellsCount[ownProc] = subdist[ownProc];
 
@@ -172,7 +172,7 @@ void Foam::decompositionInformation::printDetails(Ostream& os) const
 
     forAll(distrib_, ownProc)
     {
-        const labelList& subdist = distrib_[ownProc];
+        const labelUList& subdist = distrib_[ownProc];
 
         // First pass:
         label neighCount = 0;
diff --git a/src/parallel/decompose/decompose/decompositionModel.C b/src/parallel/decompose/decompose/decompositionModel.cxx
similarity index 100%
rename from src/parallel/decompose/decompose/decompositionModel.C
rename to src/parallel/decompose/decompose/decompositionModel.cxx
diff --git a/src/parallel/decompose/decompose/dimFieldDecomposer.H b/src/parallel/decompose/decompose/dimFieldDecomposer.H
index 01cd176339..8cd3a1ba8f 100644
--- a/src/parallel/decompose/decompose/dimFieldDecomposer.H
+++ b/src/parallel/decompose/decompose/dimFieldDecomposer.H
@@ -31,8 +31,8 @@ Description
     Dimensioned field decomposer.
 
 SourceFiles
-    dimFieldDecomposer.C
-    dimFieldDecomposerTemplates.C
+    dimFieldDecomposer.cxx
+    dimFieldDecomposer.txx
 
 \*---------------------------------------------------------------------------*/
 
@@ -40,7 +40,7 @@ SourceFiles
 #define Foam_dimFieldDecomposer_H
 
 #include "fvMesh.H"
-#include "surfaceFields.H"
+#include "DimensionedField.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -59,10 +59,10 @@ class dimFieldDecomposer
         const fvMesh& procMesh_;
 
         //- Reference to face addressing
-        //UNUSED: const labelList& faceAddressing_;
+        //UNUSED: const labelUList& faceAddressing_;
 
         //- Reference to cell addressing
-        const labelList& cellAddressing_;
+        const labelUList& cellAddressing_;
 
 
 public:
@@ -80,7 +80,7 @@ public:
         dimFieldDecomposer
         (
             const fvMesh& procMesh,
-            const labelList& cellAddressing
+            const labelUList& cellAddressing
         );
 
         //- Construct from components with API as per fvFieldDecomposer
@@ -88,8 +88,8 @@ public:
         (
             const fvMesh& completeMesh,         //!< unused
             const fvMesh& procMesh,
-            const labelList& faceAddressing,    //!< unused
-            const labelList& cellAddressing
+            const labelUList& faceAddressing,   //!< unused
+            const labelUList& cellAddressing
         );
 
 
@@ -110,7 +110,7 @@ public:
 
         //- Decompose list of fields
         template<class GeoField>
-        void decomposeFields(const PtrList<GeoField>& fields) const;
+        void decomposeFields(const UPtrList<GeoField>& fields) const;
 };
 
 
@@ -121,7 +121,7 @@ public:
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 #ifdef NoRepository
-    #include "dimFieldDecomposerTemplates.C"
+    #include "dimFieldDecomposer.txx"
 #endif
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/parallel/decompose/decompose/dimFieldDecomposer.C b/src/parallel/decompose/decompose/dimFieldDecomposer.cxx
similarity index 93%
rename from src/parallel/decompose/decompose/dimFieldDecomposer.C
rename to src/parallel/decompose/decompose/dimFieldDecomposer.cxx
index dbef4df61e..c83ad5e0f8 100644
--- a/src/parallel/decompose/decompose/dimFieldDecomposer.C
+++ b/src/parallel/decompose/decompose/dimFieldDecomposer.cxx
@@ -33,7 +33,7 @@ License
 Foam::dimFieldDecomposer::dimFieldDecomposer
 (
     const fvMesh& procMesh,
-    const labelList& cellAddressing
+    const labelUList& cellAddressing
 )
 :
     procMesh_(procMesh),
@@ -45,8 +45,8 @@ Foam::dimFieldDecomposer::dimFieldDecomposer
 (
     const fvMesh& /* unused: completeMesh */,
     const fvMesh& procMesh,
-    const labelList& /* unused: faceAddressing */,
-    const labelList& cellAddressing
+    const labelUList& /* unused: faceAddressing */,
+    const labelUList& cellAddressing
 )
 :
     procMesh_(procMesh),
diff --git a/src/parallel/decompose/decompose/dimFieldDecomposerTemplates.C b/src/parallel/decompose/decompose/dimFieldDecomposer.txx
similarity index 98%
rename from src/parallel/decompose/decompose/dimFieldDecomposerTemplates.C
rename to src/parallel/decompose/decompose/dimFieldDecomposer.txx
index 4ffa33ec85..14151a62c6 100644
--- a/src/parallel/decompose/decompose/dimFieldDecomposerTemplates.C
+++ b/src/parallel/decompose/decompose/dimFieldDecomposer.txx
@@ -54,7 +54,7 @@ Foam::dimFieldDecomposer::decomposeField
 template<class GeoField>
 void Foam::dimFieldDecomposer::decomposeFields
 (
-    const PtrList<GeoField>& fields
+    const UPtrList<GeoField>& fields
 ) const
 {
     for (const auto& fld : fields)
diff --git a/src/parallel/decompose/decompose/fvFieldDecomposer.H b/src/parallel/decompose/decompose/fvFieldDecomposer.H
index 5731951494..9f8895bdbd 100644
--- a/src/parallel/decompose/decompose/fvFieldDecomposer.H
+++ b/src/parallel/decompose/decompose/fvFieldDecomposer.H
@@ -31,9 +31,9 @@ Description
     Finite Volume volume and surface field decomposer.
 
 SourceFiles
-    fvFieldDecomposer.C
-    fvFieldDecomposerCache.C
-    fvFieldDecomposerTemplates.C
+    fvFieldDecomposer.cxx
+    fvFieldDecomposer.txx
+    fvFieldDecomposerCache.cxx
 
 \*---------------------------------------------------------------------------*/
 
@@ -42,6 +42,7 @@ SourceFiles
 
 #include "fvMesh.H"
 #include "fvPatchFieldMapper.H"
+#include "volFields.H"
 #include "surfaceFields.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -62,6 +63,9 @@ public:
 
     // Public Classes
 
+        //- Internal caching for field reading
+        class fieldsCache;
+
         //- Patch field decomposer class
         class patchFieldDecomposer
         :
@@ -85,23 +89,23 @@ public:
 
             // Member Functions
 
-                label size() const
+                label size() const noexcept
                 {
                     return directAddressing_.size();
                 }
 
-                bool direct() const
+                bool direct() const noexcept
                 {
                     return true;
                 }
 
                 //- Are there unmapped values
-                bool hasUnmapped() const
+                bool hasUnmapped() const noexcept
                 {
                     return false;
                 }
 
-                const labelUList& directAddressing() const
+                const labelUList& directAddressing() const noexcept
                 {
                     return directAddressing_;
                 }
@@ -139,23 +143,23 @@ public:
 
             // Member Functions
 
-                label size() const
+                label size() const noexcept
                 {
                     return directAddressing_.size();
                 }
 
-                bool direct() const
+                bool direct() const noexcept
                 {
                     return true;
                 }
 
                 //- Are there unmapped values
-                bool hasUnmapped() const
+                bool hasUnmapped() const noexcept
                 {
                     return false;
                 }
 
-                const labelUList& directAddressing() const
+                const labelUList& directAddressing() const noexcept
                 {
                     return directAddressing_;
                 }
@@ -174,36 +178,36 @@ public:
         public:
 
             //- Construct given addressing
-            processorSurfacePatchFieldDecomposer
+            explicit processorSurfacePatchFieldDecomposer
             (
                 const labelUList& addressingSlice
             );
 
 
-            // Member functions
+            // Member Functions
 
-                label size() const
+                label size() const noexcept
                 {
                     return addressing_.size();
                 }
 
-                bool direct() const
+                bool direct() const noexcept
                 {
                     return false;
                 }
 
                 //- Are there unmapped values
-                bool hasUnmapped() const
+                bool hasUnmapped() const noexcept
                 {
                     return false;
                 }
 
-                const labelListList& addressing() const
+                const labelListList& addressing() const noexcept
                 {
                     return addressing_;
                 }
 
-                const scalarListList& weights() const
+                const scalarListList& weights() const noexcept
                 {
                     return weights_;
                 }
@@ -218,13 +222,13 @@ private:
         const fvMesh& procMesh_;
 
         //- Reference to face addressing
-        const labelList& faceAddressing_;
+        const labelUList& faceAddressing_;
 
         //- Reference to cell addressing
-        const labelList& cellAddressing_;
+        const labelUList& cellAddressing_;
 
         //- Reference to boundary addressing
-        const labelList& boundaryAddressing_;
+        const labelUList& boundaryAddressing_;
 
         //- List of patch field decomposers
         PtrList<patchFieldDecomposer> patchFieldDecomposerPtrs_;
@@ -248,10 +252,6 @@ private:
 
 public:
 
-    // Public Classes
-    class fieldsCache;
-
-
     // Static Data
 
         //- Output verbosity when writing
@@ -263,11 +263,11 @@ public:
         //- Construct without mappers, added later with reset()
         fvFieldDecomposer
         (
-            const Foam::zero,
+            Foam::zero,
             const fvMesh& procMesh,
-            const labelList& faceAddressing,
-            const labelList& cellAddressing,
-            const labelList& boundaryAddressing
+            const labelUList& faceAddressing,
+            const labelUList& cellAddressing,
+            const labelUList& boundaryAddressing
         );
 
         //- Construct from components using information from the complete mesh
@@ -275,24 +275,24 @@ public:
         (
             const fvMesh& completeMesh,
             const fvMesh& procMesh,
-            const labelList& faceAddressing,
-            const labelList& cellAddressing,
-            const labelList& boundaryAddressing
+            const labelUList& faceAddressing,
+            const labelUList& cellAddressing,
+            const labelUList& boundaryAddressing
         );
 
         //- Construct from components without the complete mesh
         fvFieldDecomposer
         (
             // Information about the complete mesh
-            const List<labelRange>& boundaryRanges,
+            const UList<labelRange>& boundaryRanges,
             const labelUList& faceOwner,
             const labelUList& faceNeigbour,
 
             // Addressing for processor mesh
             const fvMesh& procMesh,
-            const labelList& faceAddressing,
-            const labelList& cellAddressing,
-            const labelList& boundaryAddressing
+            const labelUList& faceAddressing,
+            const labelUList& cellAddressing,
+            const labelUList& boundaryAddressing
         );
 
 
@@ -303,7 +303,7 @@ public:
     // Member Functions
 
         //- True if no mappers have been allocated
-        bool empty() const;
+        bool empty() const noexcept;
 
         //- Remove all mappers
         void clear();
@@ -314,7 +314,7 @@ public:
         //- Reset mapper using information about the complete mesh
         void reset
         (
-            const List<labelRange>& boundaryRanges,
+            const UList<labelRange>& boundaryRanges,
             const labelUList& faceOwner,
             const labelUList& faceNeigbour
         );
@@ -349,7 +349,7 @@ public:
 
         //- Decompose list of fields
         template<class GeoField>
-        void decomposeFields(const PtrList<GeoField>& fields) const;
+        void decomposeFields(const UPtrList<GeoField>& fields) const;
 };
 
 
@@ -359,21 +359,14 @@ public:
 
 class fvFieldDecomposer::fieldsCache
 {
-    // Private Data
+    class privateCache;
+    std::unique_ptr<privateCache> cache_;
 
-        class privateCache;
+    //- No copy construct
+    fieldsCache(const fieldsCache&) = delete;
 
-        //- All field and field-field types for lagrangian
-        std::unique_ptr<privateCache> cache_;
-
-
-    // Private Member Functions
-
-        //- No copy construct
-        fieldsCache(const fieldsCache&) = delete;
-
-        //- No copy assignment
-        void operator=(const fieldsCache&) = delete;
+    //- No copy assignment
+    void operator=(const fieldsCache&) = delete;
 
 
 public:
@@ -391,10 +384,10 @@ public:
     // Member Functions
 
         //- No fields
-        bool empty() const;
+        bool empty() const noexcept;
 
         //- Total number of fields
-        label size() const;
+        label size() const noexcept;
 
         //- Clear out
         void clear();
@@ -423,7 +416,7 @@ public:
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 #ifdef NoRepository
-    #include "fvFieldDecomposerTemplates.C"
+    #include "fvFieldDecomposer.txx"
 #endif
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/parallel/decompose/decompose/fvFieldDecomposer.C b/src/parallel/decompose/decompose/fvFieldDecomposer.cxx
similarity index 84%
rename from src/parallel/decompose/decompose/fvFieldDecomposer.C
rename to src/parallel/decompose/decompose/fvFieldDecomposer.cxx
index 7a1c0116e2..9f573f91ea 100644
--- a/src/parallel/decompose/decompose/fvFieldDecomposer.C
+++ b/src/parallel/decompose/decompose/fvFieldDecomposer.cxx
@@ -135,22 +135,17 @@ processorSurfacePatchFieldDecomposer
 
 Foam::fvFieldDecomposer::fvFieldDecomposer
 (
-    const Foam::zero,
+    Foam::zero,
     const fvMesh& procMesh,
-    const labelList& faceAddressing,
-    const labelList& cellAddressing,
-    const labelList& boundaryAddressing
+    const labelUList& faceAddressing,
+    const labelUList& cellAddressing,
+    const labelUList& boundaryAddressing
 )
 :
     procMesh_(procMesh),
     faceAddressing_(faceAddressing),
     cellAddressing_(cellAddressing),
-    boundaryAddressing_(boundaryAddressing),
-    // Mappers
-    patchFieldDecomposerPtrs_(),
-    processorVolPatchFieldDecomposerPtrs_(),
-    processorSurfacePatchFieldDecomposerPtrs_(),
-    faceSign_()
+    boundaryAddressing_(boundaryAddressing)
 {}
 
 
@@ -158,14 +153,14 @@ Foam::fvFieldDecomposer::fvFieldDecomposer
 (
     const fvMesh& completeMesh,
     const fvMesh& procMesh,
-    const labelList& faceAddressing,
-    const labelList& cellAddressing,
-    const labelList& boundaryAddressing
+    const labelUList& faceAddressing,
+    const labelUList& cellAddressing,
+    const labelUList& boundaryAddressing
 )
 :
     fvFieldDecomposer
     (
-        zero{},
+        Foam::zero{},
         procMesh,
         faceAddressing,
         cellAddressing,
@@ -178,19 +173,19 @@ Foam::fvFieldDecomposer::fvFieldDecomposer
 
 Foam::fvFieldDecomposer::fvFieldDecomposer
 (
-    const List<labelRange>& boundaryRanges,
+    const UList<labelRange>& boundaryRanges,
     const labelUList& faceOwner,
     const labelUList& faceNeighbour,
 
     const fvMesh& procMesh,
-    const labelList& faceAddressing,
-    const labelList& cellAddressing,
-    const labelList& boundaryAddressing
+    const labelUList& faceAddressing,
+    const labelUList& cellAddressing,
+    const labelUList& boundaryAddressing
 )
 :
     fvFieldDecomposer
     (
-        zero{},
+        Foam::zero{},
         procMesh,
         faceAddressing,
         cellAddressing,
@@ -203,7 +198,7 @@ Foam::fvFieldDecomposer::fvFieldDecomposer
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-bool Foam::fvFieldDecomposer::empty() const
+bool Foam::fvFieldDecomposer::empty() const noexcept
 {
     return patchFieldDecomposerPtrs_.empty();
 }
@@ -220,17 +215,17 @@ void Foam::fvFieldDecomposer::clear()
 
 void Foam::fvFieldDecomposer::reset
 (
-    const List<labelRange>& boundaryRanges,
+    const UList<labelRange>& boundaryRanges,
     const labelUList& faceOwner,
     const labelUList& faceNeighbour
 )
 {
-    clear();
     const label nMappers = procMesh_.boundary().size();
-    patchFieldDecomposerPtrs_.resize(nMappers);
-    processorVolPatchFieldDecomposerPtrs_.resize(nMappers);
-    processorSurfacePatchFieldDecomposerPtrs_.resize(nMappers);
-    faceSign_.resize(nMappers);
+
+    patchFieldDecomposerPtrs_.resize_null(nMappers);
+    processorVolPatchFieldDecomposerPtrs_.resize_null(nMappers);
+    processorSurfacePatchFieldDecomposerPtrs_.resize_null(nMappers);
+    faceSign_.resize_null(nMappers);
 
     forAll(boundaryAddressing_, patchi)
     {
@@ -270,10 +265,7 @@ void Foam::fvFieldDecomposer::reset
             processorSurfacePatchFieldDecomposerPtrs_.set
             (
                 patchi,
-                new processorSurfacePatchFieldDecomposer
-                (
-                    static_cast<const labelUList&>(localPatchSlice)
-                )
+                new processorSurfacePatchFieldDecomposer(localPatchSlice)
             );
 
             faceSign_.set
@@ -296,12 +288,12 @@ void Foam::fvFieldDecomposer::reset
 
 void Foam::fvFieldDecomposer::reset(const fvMesh& completeMesh)
 {
-    clear();
     const label nMappers = procMesh_.boundary().size();
-    patchFieldDecomposerPtrs_.resize(nMappers);
-    processorVolPatchFieldDecomposerPtrs_.resize(nMappers);
-    processorSurfacePatchFieldDecomposerPtrs_.resize(nMappers);
-    faceSign_.resize(nMappers);
+
+    patchFieldDecomposerPtrs_.resize_null(nMappers);
+    processorVolPatchFieldDecomposerPtrs_.resize_null(nMappers);
+    processorSurfacePatchFieldDecomposerPtrs_.resize_null(nMappers);
+    faceSign_.resize_null(nMappers);
 
     forAll(boundaryAddressing_, patchi)
     {
@@ -340,10 +332,7 @@ void Foam::fvFieldDecomposer::reset(const fvMesh& completeMesh)
             processorSurfacePatchFieldDecomposerPtrs_.set
             (
                 patchi,
-                new processorSurfacePatchFieldDecomposer
-                (
-                    static_cast<const labelUList&>(localPatchSlice)
-                )
+                new processorSurfacePatchFieldDecomposer(localPatchSlice)
             );
 
             faceSign_.set
diff --git a/src/parallel/decompose/decompose/fvFieldDecomposerTemplates.C b/src/parallel/decompose/decompose/fvFieldDecomposer.txx
similarity index 99%
rename from src/parallel/decompose/decompose/fvFieldDecomposerTemplates.C
rename to src/parallel/decompose/decompose/fvFieldDecomposer.txx
index 9e5cfd727b..40f2699247 100644
--- a/src/parallel/decompose/decompose/fvFieldDecomposerTemplates.C
+++ b/src/parallel/decompose/decompose/fvFieldDecomposer.txx
@@ -295,7 +295,7 @@ Foam::fvFieldDecomposer::decomposeField
 template<class GeoField>
 void Foam::fvFieldDecomposer::decomposeFields
 (
-    const PtrList<GeoField>& fields
+    const UPtrList<GeoField>& fields
 ) const
 {
     for (const auto& fld : fields)
diff --git a/src/parallel/decompose/decompose/fvFieldDecomposerCache.C b/src/parallel/decompose/decompose/fvFieldDecomposerCache.cxx
similarity index 97%
rename from src/parallel/decompose/decompose/fvFieldDecomposerCache.C
rename to src/parallel/decompose/decompose/fvFieldDecomposerCache.cxx
index 27bdee2aeb..08301abd39 100644
--- a/src/parallel/decompose/decompose/fvFieldDecomposerCache.C
+++ b/src/parallel/decompose/decompose/fvFieldDecomposerCache.cxx
@@ -119,7 +119,7 @@ public:
     static void decompose
     (
         const fvFieldDecomposer& decomposer,
-        const PtrList<GeoField>& fields,
+        const UPtrList<GeoField>& fields,
         bool report
     )
     {
@@ -181,13 +181,13 @@ Foam::fvFieldDecomposer::fieldsCache::~fieldsCache()
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-bool Foam::fvFieldDecomposer::fieldsCache::empty() const
+bool Foam::fvFieldDecomposer::fieldsCache::empty() const noexcept
 {
     return (!cache_ || cache_->empty());
 }
 
 
-Foam::label Foam::fvFieldDecomposer::fieldsCache::size() const
+Foam::label Foam::fvFieldDecomposer::fieldsCache::size() const noexcept
 {
     return (cache_ ? cache_->size() : label(0));
 }
diff --git a/src/parallel/decompose/decompose/lagrangianFieldDecomposer.H b/src/parallel/decompose/decompose/lagrangianFieldDecomposer.H
index 66284c6fc8..01be977328 100644
--- a/src/parallel/decompose/decompose/lagrangianFieldDecomposer.H
+++ b/src/parallel/decompose/decompose/lagrangianFieldDecomposer.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2022 OpenCFD Ltd.
+    Copyright (C) 2022-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -31,10 +31,9 @@ Description
     Lagrangian field decomposer.
 
 SourceFiles
-    lagrangianFieldDecomposer.C
-    lagrangianFieldDecomposerCache.C
-    lagrangianFieldDecomposerReadFields.C
-    lagrangianFieldDecomposerTemplates.C
+    lagrangianFieldDecomposer.cxx
+    lagrangianFieldDecomposer.txx
+    lagrangianFieldDecomposerCache.cxx
 
 \*---------------------------------------------------------------------------*/
 
@@ -92,13 +91,13 @@ public:
         //- Construct from components
         lagrangianFieldDecomposer
         (
-            const polyMesh& mesh,       //<! unused
+            const polyMesh& mesh,       //!< unused
             const polyMesh& procMesh,
-            const labelList& faceProcAddressing,
-            const labelList& cellProcAddressing,
+            const labelUList& faceProcAddressing,
+            const labelUList& cellProcAddressing,
             const word& cloudName,
             const Cloud<indexedParticle>& lagrangianPositions,
-            const List<SLList<indexedParticle*>*>& cellParticles
+            const UList<SLList<indexedParticle*>*>& cellParticles
         );
 
 
@@ -125,7 +124,7 @@ public:
 
     // Member Functions
 
-        //- Decompose volume field
+        //- Decompose field
         template<class Type>
         tmp<IOField<Type>> decomposeField
         (
@@ -133,6 +132,7 @@ public:
             const IOField<Type>& field
         ) const;
 
+        //- Decompose field-field
         template<class Type>
         tmp<CompactIOField<Field<Type>>> decomposeFieldField
         (
@@ -141,18 +141,20 @@ public:
         ) const;
 
 
+        //- Decompose fields
         template<class GeoField>
         void decomposeFields
         (
             const word& cloudName,
-            const PtrList<GeoField>& fields
+            const UPtrList<GeoField>& fields
         ) const;
 
+        //- Decompose field-fields
         template<class GeoField>
         void decomposeFieldFields
         (
             const word& cloudName,
-            const PtrList<GeoField>& fields
+            const UPtrList<GeoField>& fields
         ) const;
 };
 
@@ -163,21 +165,14 @@ public:
 
 class lagrangianFieldDecomposer::fieldsCache
 {
-    // Private Data
+    class privateCache;
+    std::unique_ptr<privateCache> cache_;
 
-        class privateCache;
+    //- No copy construct
+    fieldsCache(const fieldsCache&) = delete;
 
-        //- All field and field-field types for lagrangian
-        std::unique_ptr<privateCache> cache_;
-
-
-    // Private Member Functions
-
-        //- No copy construct
-        fieldsCache(const fieldsCache&) = delete;
-
-        //- No copy assignment
-        void operator=(const fieldsCache&) = delete;
+    //- No copy assignment
+    void operator=(const fieldsCache&) = delete;
 
 
 public:
@@ -188,7 +183,7 @@ public:
         fieldsCache();
 
         //- Construct for given number of clouds
-        explicit fieldsCache(const label nClouds);
+        explicit fieldsCache(label nClouds);
 
 
     //- Destructor
@@ -198,16 +193,16 @@ public:
     // Member Functions
 
         //- No clouds
-        bool empty() const;
+        bool empty() const noexcept;
 
         //- Number of clouds
-        label size() const;
+        label size() const noexcept;
 
         //- Clear out
         void clear();
 
         //- Resize for the number of clouds
-        void resize(const label nClouds);
+        void resize(label nClouds);
 
 
         //- Read all fields and field-fields for given cloud and objects
@@ -235,8 +230,7 @@ public:
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 #ifdef NoRepository
-    #include "lagrangianFieldDecomposerReadFields.C"
-    #include "lagrangianFieldDecomposerTemplates.C"
+    #include "lagrangianFieldDecomposer.txx"
 #endif
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/parallel/decompose/decompose/lagrangianFieldDecomposer.C b/src/parallel/decompose/decompose/lagrangianFieldDecomposer.cxx
similarity index 94%
rename from src/parallel/decompose/decompose/lagrangianFieldDecomposer.C
rename to src/parallel/decompose/decompose/lagrangianFieldDecomposer.cxx
index 46f3598d67..549faac857 100644
--- a/src/parallel/decompose/decompose/lagrangianFieldDecomposer.C
+++ b/src/parallel/decompose/decompose/lagrangianFieldDecomposer.cxx
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
+    Copyright (C) 2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -23,9 +24,6 @@ License
     You should have received a copy of the GNU General Public License
     along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
-Description
-    Lagrangian field decomposer.
-
 \*---------------------------------------------------------------------------*/
 
 #include "lagrangianFieldDecomposer.H"
@@ -36,11 +34,11 @@ Foam::lagrangianFieldDecomposer::lagrangianFieldDecomposer
 (
     const polyMesh& mesh,
     const polyMesh& procMesh,
-    const labelList& faceProcAddressing,
-    const labelList& cellProcAddressing,
+    const labelUList& faceProcAddressing,
+    const labelUList& cellProcAddressing,
     const word& cloudName,
     const Cloud<indexedParticle>& lagrangianPositions,
-    const List<SLList<indexedParticle*>*>& cellParticles
+    const UList<SLList<indexedParticle*>*>& cellParticles
 )
 :
     procMesh_(procMesh),
diff --git a/src/parallel/decompose/decompose/lagrangianFieldDecomposerTemplates.C b/src/parallel/decompose/decompose/lagrangianFieldDecomposer.txx
similarity index 67%
rename from src/parallel/decompose/decompose/lagrangianFieldDecomposerTemplates.C
rename to src/parallel/decompose/decompose/lagrangianFieldDecomposer.txx
index 7df4964718..dfa14bc928 100644
--- a/src/parallel/decompose/decompose/lagrangianFieldDecomposerTemplates.C
+++ b/src/parallel/decompose/decompose/lagrangianFieldDecomposer.txx
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2022 OpenCFD Ltd.
+    Copyright (C) 2022-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -31,6 +31,64 @@ License
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
+template<class Type>
+void Foam::lagrangianFieldDecomposer::readFields
+(
+    const label cloudi,
+    const IOobjectList& lagrangianObjects,
+    PtrList<PtrList<IOField<Type>>>& lagrangianFields
+)
+{
+    // Lagrangian field objects
+    const UPtrList<const IOobject> fieldObjects
+    (
+        lagrangianObjects.csorted<IOField<Type>>()
+    );
+
+
+    auto& cloudFields =
+        lagrangianFields.emplace_set(cloudi, fieldObjects.size());
+
+    forAll(fieldObjects, fieldi)
+    {
+        cloudFields.emplace_set(fieldi, fieldObjects[fieldi]);
+    }
+}
+
+
+template<class Type>
+void Foam::lagrangianFieldDecomposer::readFieldFields
+(
+    const label cloudi,
+    const IOobjectList& lagrangianObjects,
+    PtrList<PtrList<CompactIOField<Field<Type>>>>& lagrangianFields
+)
+{
+    // Lagrangian field objects
+    UPtrList<const IOobject> fieldObjects
+    (
+        lagrangianObjects.cobjects<IOField<Field<Type>>>()
+    );
+
+    // Lagrangian field-field objects
+    fieldObjects.push_back
+    (
+        lagrangianObjects.cobjects<CompactIOField<Field<Type>>>()
+    );
+
+    Foam::sort(fieldObjects, nameOp<IOobject>());
+
+
+    auto& cloudFields =
+        lagrangianFields.emplace_set(cloudi, fieldObjects.size());
+
+    forAll(fieldObjects, fieldi)
+    {
+        cloudFields.emplace_set(fieldi, fieldObjects[fieldi]);
+    }
+}
+
+
 template<class Type>
 Foam::tmp<Foam::IOField<Type>>
 Foam::lagrangianFieldDecomposer::decomposeField
@@ -89,10 +147,10 @@ template<class GeoField>
 void Foam::lagrangianFieldDecomposer::decomposeFields
 (
     const word& cloudName,
-    const PtrList<GeoField>& fields
+    const UPtrList<GeoField>& fields
 ) const
 {
-    const bool existsOnProc = (particleIndices_.size() > 0);
+    const bool existsOnProc = (!particleIndices_.empty());
 
     for (const GeoField& fld : fields)
     {
@@ -105,10 +163,10 @@ template<class GeoField>
 void Foam::lagrangianFieldDecomposer::decomposeFieldFields
 (
     const word& cloudName,
-    const PtrList<GeoField>& fields
+    const UPtrList<GeoField>& fields
 ) const
 {
-    const bool existsOnProc = (particleIndices_.size() > 0);
+    const bool existsOnProc = (!particleIndices_.empty());
 
     for (const GeoField& fld : fields)
     {
diff --git a/src/parallel/decompose/decompose/lagrangianFieldDecomposerCache.C b/src/parallel/decompose/decompose/lagrangianFieldDecomposerCache.cxx
similarity index 97%
rename from src/parallel/decompose/decompose/lagrangianFieldDecomposerCache.C
rename to src/parallel/decompose/decompose/lagrangianFieldDecomposerCache.cxx
index 9edb3c1e79..79a9009d67 100644
--- a/src/parallel/decompose/decompose/lagrangianFieldDecomposerCache.C
+++ b/src/parallel/decompose/decompose/lagrangianFieldDecomposerCache.cxx
@@ -160,10 +160,7 @@ Foam::lagrangianFieldDecomposer::fieldsCache::fieldsCache()
 {}
 
 
-Foam::lagrangianFieldDecomposer::fieldsCache::fieldsCache
-(
-    const label nClouds
-)
+Foam::lagrangianFieldDecomposer::fieldsCache::fieldsCache(label nClouds)
 :
     cache_(new privateCache)
 {
@@ -180,13 +177,13 @@ Foam::lagrangianFieldDecomposer::fieldsCache::~fieldsCache()
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-bool Foam::lagrangianFieldDecomposer::fieldsCache::empty() const
+bool Foam::lagrangianFieldDecomposer::fieldsCache::empty() const noexcept
 {
     return (!cache_ || cache_->empty());
 }
 
 
-Foam::label Foam::lagrangianFieldDecomposer::fieldsCache::size() const
+Foam::label Foam::lagrangianFieldDecomposer::fieldsCache::size() const noexcept
 {
     return (cache_ ? cache_->size() : label(0));
 }
@@ -198,10 +195,7 @@ void Foam::lagrangianFieldDecomposer::fieldsCache::clear()
 }
 
 
-void Foam::lagrangianFieldDecomposer::fieldsCache::resize
-(
-    const label nClouds
-)
+void Foam::lagrangianFieldDecomposer::fieldsCache::resize(label nClouds)
 {
     if (cache_)
     {
diff --git a/src/parallel/decompose/decompose/lagrangianFieldDecomposerReadFields.C b/src/parallel/decompose/decompose/lagrangianFieldDecomposerReadFields.C
deleted file mode 100644
index 954636cba7..0000000000
--- a/src/parallel/decompose/decompose/lagrangianFieldDecomposerReadFields.C
+++ /dev/null
@@ -1,90 +0,0 @@
-/*---------------------------------------------------------------------------*\
-  =========                 |
-  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
-   \\    /   O peration     |
-    \\  /    A nd           | www.openfoam.com
-     \\/     M anipulation  |
--------------------------------------------------------------------------------
-    Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2022-2023 OpenCFD Ltd.
--------------------------------------------------------------------------------
-License
-    This file is part of OpenFOAM.
-
-    OpenFOAM is free software: you can redistribute it and/or modify it
-    under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
-    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-    for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
-
-\*---------------------------------------------------------------------------*/
-
-#include "lagrangianFieldDecomposer.H"
-#include "IOobjectList.H"
-
-// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
-
-template<class Type>
-void Foam::lagrangianFieldDecomposer::readFields
-(
-    const label cloudi,
-    const IOobjectList& lagrangianObjects,
-    PtrList<PtrList<IOField<Type>>>& lagrangianFields
-)
-{
-    // List of lagrangian field objects
-    const UPtrList<const IOobject> fieldObjects
-    (
-        lagrangianObjects.csorted<IOField<Type>>()
-    );
-
-    auto& cloudFields =
-        lagrangianFields.emplace_set(cloudi, fieldObjects.size());
-
-    forAll(fieldObjects, fieldi)
-    {
-        cloudFields.emplace_set(fieldi, fieldObjects[fieldi]);
-    }
-}
-
-
-template<class Type>
-void Foam::lagrangianFieldDecomposer::readFieldFields
-(
-    const label cloudi,
-    const IOobjectList& lagrangianObjects,
-    PtrList<PtrList<CompactIOField<Field<Type>>>>& lagrangianFields
-)
-{
-    // List of lagrangian field objects
-    UPtrList<const IOobject> fieldObjects
-    (
-        lagrangianObjects.cobjects<IOField<Field<Type>>>()
-    );
-
-    fieldObjects.push_back
-    (
-        lagrangianObjects.cobjects<CompactIOField<Field<Type>>>()
-    );
-
-    Foam::sort(fieldObjects, nameOp<IOobject>());
-
-
-    auto& cloudFields =
-        lagrangianFields.emplace_set(cloudi, fieldObjects.size());
-
-    forAll(fieldObjects, fieldi)
-    {
-        cloudFields.emplace_set(fieldi, fieldObjects[fieldi]);
-    }
-}
-
-
-// ************************************************************************* //
diff --git a/src/parallel/decompose/decompose/pointFieldDecomposer.H b/src/parallel/decompose/decompose/pointFieldDecomposer.H
index b49ae3ce9f..c6567b2ca2 100644
--- a/src/parallel/decompose/decompose/pointFieldDecomposer.H
+++ b/src/parallel/decompose/decompose/pointFieldDecomposer.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2021-2022 OpenCFD Ltd.
+    Copyright (C) 2021-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -31,9 +31,9 @@ Description
     Point field decomposer.
 
 SourceFiles
-    pointFieldDecomposer.C
-    pointFieldDecomposerCache.C
-    pointFieldDecomposerTemplates.C
+    pointFieldDecomposer.cxx
+    pointFieldDecomposer.txx
+    pointFieldDecomposerCache.cxx
 
 \*---------------------------------------------------------------------------*/
 
@@ -41,8 +41,8 @@ SourceFiles
 #define Foam_pointFieldDecomposer_H
 
 #include "pointMesh.H"
-#include "pointPatchFieldMapperPatchRef.H"
 #include "pointFields.H"
+#include "pointPatchFieldMapper.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -62,12 +62,15 @@ public:
 
     // Public Classes
 
+        //- Internal caching for field reading
+        class fieldsCache;
+
         //- Point patch field decomposer class
         class patchFieldDecomposer
         :
-            public pointPatchFieldMapperPatchRef
+            public pointPatchFieldMapper
         {
-            // Private data
+            // Private Data
 
                 labelList directAddressing_;
 
@@ -83,28 +86,28 @@ public:
                 (
                     const pointPatch& completeMeshPatch,
                     const pointPatch& procMeshPatch,
-                    const labelList& directAddr
+                    const labelUList& directAddr
                 );
 
 
-            // Member functions
+            // Member Functions
 
-                label size() const
+                label size() const noexcept
                 {
                     return directAddressing_.size();
                 }
 
-                bool direct() const
+                bool direct() const noexcept
                 {
                     return true;
                 }
 
-                bool hasUnmapped() const
+                bool hasUnmapped() const noexcept
                 {
                     return hasUnmapped_;
                 }
 
-                const labelUList& directAddressing() const
+                const labelUList& directAddressing() const noexcept
                 {
                     return directAddressing_;
                 }
@@ -119,27 +122,22 @@ private:
         const pointMesh& procMesh_;
 
         //- Reference to point addressing
-        const labelList& pointAddressing_;
+        const labelUList& pointAddressing_;
 
         //- Reference to boundary addressing
-        const labelList& boundaryAddressing_;
+        const labelUList& boundaryAddressing_;
 
         //- List of patch field decomposers
         PtrList<patchFieldDecomposer> patchFieldDecomposerPtrs_;
 
 
-    // Private Member Functions
-
-        //- No copy construct
-        pointFieldDecomposer(const pointFieldDecomposer&) = delete;
-
-        //- No copy assignment
-        void operator=(const pointFieldDecomposer&) = delete;
-
 public:
 
-    // Public Classes
-    class fieldsCache;
+    //- No copy construct
+    pointFieldDecomposer(const pointFieldDecomposer&) = delete;
+
+    //- No copy assignment
+    void operator=(const pointFieldDecomposer&) = delete;
 
 
     // Constructors
@@ -147,10 +145,10 @@ public:
         //- Construct without mappers, added later with reset()
         pointFieldDecomposer
         (
-            const Foam::zero,
+            Foam::zero,
             const pointMesh& procMesh,
-            const labelList& pointAddressing,
-            const labelList& boundaryAddressing
+            const labelUList& pointAddressing,
+            const labelUList& boundaryAddressing
         );
 
         //- Construct from components
@@ -158,8 +156,8 @@ public:
         (
             const pointMesh& completeMesh,
             const pointMesh& procMesh,
-            const labelList& pointAddressing,
-            const labelList& boundaryAddressing
+            const labelUList& pointAddressing,
+            const labelUList& boundaryAddressing
         );
 
 
@@ -170,7 +168,7 @@ public:
     // Member Functions
 
         //- True if no mappers have been allocated
-        bool empty() const;
+        bool empty() const noexcept;
 
         //- Remove all mappers
         void clear();
@@ -191,7 +189,7 @@ public:
 
         //- Decompose list of fields
         template<class GeoField>
-        void decomposeFields(const PtrList<GeoField>& fields) const;
+        void decomposeFields(const UPtrList<GeoField>& fields) const;
 };
 
 
@@ -201,21 +199,14 @@ public:
 
 class pointFieldDecomposer::fieldsCache
 {
-    // Private Data
+    class privateCache;
+    std::unique_ptr<privateCache> cache_;
 
-        class privateCache;
+    //- No copy construct
+    fieldsCache(const fieldsCache&) = delete;
 
-        //- All field and field-field types for lagrangian
-        std::unique_ptr<privateCache> cache_;
-
-
-    // Private Member Functions
-
-        //- No copy construct
-        fieldsCache(const fieldsCache&) = delete;
-
-        //- No copy assignment
-        void operator=(const fieldsCache&) = delete;
+    //- No copy assignment
+    void operator=(const fieldsCache&) = delete;
 
 
 public:
@@ -233,10 +224,10 @@ public:
     // Member Functions
 
         //- No fields
-        bool empty() const;
+        bool empty() const noexcept;
 
         //- Total number of fields
-        label size() const;
+        label size() const noexcept;
 
         //- Clear out
         void clear();
@@ -265,7 +256,7 @@ public:
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 #ifdef NoRepository
-    #include "pointFieldDecomposerTemplates.C"
+    #include "pointFieldDecomposer.txx"
 #endif
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/parallel/decompose/decompose/pointFieldDecomposer.C b/src/parallel/decompose/decompose/pointFieldDecomposer.cxx
similarity index 82%
rename from src/parallel/decompose/decompose/pointFieldDecomposer.C
rename to src/parallel/decompose/decompose/pointFieldDecomposer.cxx
index 4b1a29a1c5..a0ff0197a5 100644
--- a/src/parallel/decompose/decompose/pointFieldDecomposer.C
+++ b/src/parallel/decompose/decompose/pointFieldDecomposer.cxx
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2021 OpenCFD Ltd.
+    Copyright (C) 2021-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -34,21 +34,16 @@ Foam::pointFieldDecomposer::patchFieldDecomposer::patchFieldDecomposer
 (
     const pointPatch& completeMeshPatch,
     const pointPatch& procMeshPatch,
-    const labelList& directAddr
+    const labelUList& directAddr
 )
 :
-    pointPatchFieldMapperPatchRef
-    (
-        completeMeshPatch,
-        procMeshPatch
-    ),
     directAddressing_(procMeshPatch.size(), -1),
     hasUnmapped_(false)
 {
     // Create the inverse-addressing of the patch point labels.
     labelList pointMap(completeMeshPatch.boundaryMesh().mesh().size(), -1);
 
-    const labelList& completeMeshPatchPoints = completeMeshPatch.meshPoints();
+    const labelUList& completeMeshPatchPoints = completeMeshPatch.meshPoints();
 
     forAll(completeMeshPatchPoints, pointi)
     {
@@ -57,7 +52,7 @@ Foam::pointFieldDecomposer::patchFieldDecomposer::patchFieldDecomposer
 
     // Use the inverse point addressing to create the addressing table for this
     // patch
-    const labelList& procMeshPatchPoints = procMeshPatch.meshPoints();
+    const labelUList& procMeshPatchPoints = procMeshPatch.meshPoints();
 
     forAll(procMeshPatchPoints, pointi)
     {
@@ -66,7 +61,7 @@ Foam::pointFieldDecomposer::patchFieldDecomposer::patchFieldDecomposer
     }
 
     // Check that all the patch point addresses are set
-    if (directAddressing_.size() && min(directAddressing_) < 0)
+    if (directAddressing_.contains(-1))
     {
         hasUnmapped_ = true;
 
@@ -79,17 +74,15 @@ Foam::pointFieldDecomposer::patchFieldDecomposer::patchFieldDecomposer
 
 Foam::pointFieldDecomposer::pointFieldDecomposer
 (
-    const Foam::zero,
+    Foam::zero,
     const pointMesh& procMesh,
-    const labelList& pointAddressing,
-    const labelList& boundaryAddressing
+    const labelUList& pointAddressing,
+    const labelUList& boundaryAddressing
 )
 :
     procMesh_(procMesh),
     pointAddressing_(pointAddressing),
-    boundaryAddressing_(boundaryAddressing),
-    // Mappers
-    patchFieldDecomposerPtrs_()
+    boundaryAddressing_(boundaryAddressing)
 {}
 
 
@@ -97,13 +90,13 @@ Foam::pointFieldDecomposer::pointFieldDecomposer
 (
     const pointMesh& completeMesh,
     const pointMesh& procMesh,
-    const labelList& pointAddressing,
-    const labelList& boundaryAddressing
+    const labelUList& pointAddressing,
+    const labelUList& boundaryAddressing
 )
 :
     pointFieldDecomposer
     (
-        zero{},
+        Foam::zero{},
         procMesh,
         pointAddressing,
         boundaryAddressing
@@ -115,7 +108,7 @@ Foam::pointFieldDecomposer::pointFieldDecomposer
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-bool Foam::pointFieldDecomposer::empty() const
+bool Foam::pointFieldDecomposer::empty() const noexcept
 {
     return patchFieldDecomposerPtrs_.empty();
 }
@@ -132,9 +125,9 @@ void Foam::pointFieldDecomposer::reset
     const pointMesh& completeMesh
 )
 {
-    clear();
     const label nMappers = procMesh_.boundary().size();
-    patchFieldDecomposerPtrs_.resize(nMappers);
+
+    patchFieldDecomposerPtrs_.resize_null(nMappers);
 
     forAll(boundaryAddressing_, patchi)
     {
diff --git a/src/parallel/decompose/decompose/pointFieldDecomposerTemplates.C b/src/parallel/decompose/decompose/pointFieldDecomposer.txx
similarity index 98%
rename from src/parallel/decompose/decompose/pointFieldDecomposerTemplates.C
rename to src/parallel/decompose/decompose/pointFieldDecomposer.txx
index cc2671e98f..73fc2d0029 100644
--- a/src/parallel/decompose/decompose/pointFieldDecomposerTemplates.C
+++ b/src/parallel/decompose/decompose/pointFieldDecomposer.txx
@@ -90,7 +90,7 @@ Foam::pointFieldDecomposer::decomposeField
 template<class GeoField>
 void Foam::pointFieldDecomposer::decomposeFields
 (
-    const PtrList<GeoField>& fields
+    const UPtrList<GeoField>& fields
 ) const
 {
     for (const auto& fld : fields)
diff --git a/src/parallel/decompose/decompose/pointFieldDecomposerCache.C b/src/parallel/decompose/decompose/pointFieldDecomposerCache.cxx
similarity index 97%
rename from src/parallel/decompose/decompose/pointFieldDecomposerCache.C
rename to src/parallel/decompose/decompose/pointFieldDecomposerCache.cxx
index 69f683e600..21befb2608 100644
--- a/src/parallel/decompose/decompose/pointFieldDecomposerCache.C
+++ b/src/parallel/decompose/decompose/pointFieldDecomposerCache.cxx
@@ -101,7 +101,7 @@ public:
     static void decompose
     (
         const pointFieldDecomposer& decomposer,
-        const PtrList<GeoField>& fields,
+        const UPtrList<GeoField>& fields,
         bool report
     )
     {
@@ -161,13 +161,13 @@ Foam::pointFieldDecomposer::fieldsCache::~fieldsCache()
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-bool Foam::pointFieldDecomposer::fieldsCache::empty() const
+bool Foam::pointFieldDecomposer::fieldsCache::empty() const noexcept
 {
     return (!cache_ || cache_->empty());
 }
 
 
-Foam::label Foam::pointFieldDecomposer::fieldsCache::size() const
+Foam::label Foam::pointFieldDecomposer::fieldsCache::size() const noexcept
 {
     return (cache_ ? cache_->size() : label(0));
 }
diff --git a/src/parallel/reconstruct/reconstruct/Make/files b/src/parallel/reconstruct/reconstruct/Make/files
index 2dbe299bfd..0c3e488e68 100644
--- a/src/parallel/reconstruct/reconstruct/Make/files
+++ b/src/parallel/reconstruct/reconstruct/Make/files
@@ -1,7 +1,7 @@
-processorMeshes.C
-fvFieldReconstructor.C
-pointFieldReconstructor.C
-passivePositionParticleCloud.C
-lagrangianReconstructor.C
+processorMeshes.cxx
+fvFieldReconstructor.cxx
+pointFieldReconstructor.cxx
+passivePositionParticleCloud.cxx
+lagrangianReconstructor.cxx
 
 LIB = $(FOAM_LIBBIN)/libreconstruct
diff --git a/src/parallel/reconstruct/reconstruct/fvFieldReconstructor.H b/src/parallel/reconstruct/reconstruct/fvFieldReconstructor.H
index d950165ba6..b37f76620b 100644
--- a/src/parallel/reconstruct/reconstruct/fvFieldReconstructor.H
+++ b/src/parallel/reconstruct/reconstruct/fvFieldReconstructor.H
@@ -31,8 +31,8 @@ Description
     Finite volume reconstructor for volume and surface fields.
 
 SourceFiles
-    fvFieldReconstructor.C
-    fvFieldReconstructorTemplates.C
+    fvFieldReconstructor.cxx
+    fvFieldReconstructor.txx
 
 \*---------------------------------------------------------------------------*/
 
@@ -62,16 +62,16 @@ class fvFieldReconstructor
         fvMesh& mesh_;
 
         //- List of processor meshes
-        const PtrList<fvMesh>& procMeshes_;
+        const UPtrList<fvMesh>& procMeshes_;
 
         //- List of processor face addressing lists
-        const PtrList<labelIOList>& faceProcAddressing_;
+        const UPtrList<labelIOList>& faceProcAddressing_;
 
         //- List of processor cell addressing lists
-        const PtrList<labelIOList>& cellProcAddressing_;
+        const UPtrList<labelIOList>& cellProcAddressing_;
 
         //- List of processor boundary addressing lists
-        const PtrList<labelIOList>& boundaryProcAddressing_;
+        const UPtrList<labelIOList>& boundaryProcAddressing_;
 
         //- Number of fields reconstructed
         label nReconstructed_;
@@ -144,10 +144,10 @@ public:
         fvFieldReconstructor
         (
             fvMesh& mesh,
-            const PtrList<fvMesh>& procMeshes,
-            const PtrList<labelIOList>& faceProcAddressing,
-            const PtrList<labelIOList>& cellProcAddressing,
-            const PtrList<labelIOList>& boundaryProcAddressing
+            const UPtrList<fvMesh>& procMeshes,
+            const UPtrList<labelIOList>& faceProcAddressing,
+            const UPtrList<labelIOList>& cellProcAddressing,
+            const UPtrList<labelIOList>& boundaryProcAddressing
         );
 
 
@@ -165,7 +165,7 @@ public:
         reconstructField
         (
             const IOobject& fieldObject,
-            const PtrList<DimensionedField<Type, volMesh>>& procFields
+            const UPtrList<DimensionedField<Type, volMesh>>& procFields
         ) const;
 
         //- Read and reconstruct volume internal field
@@ -180,7 +180,7 @@ public:
         reconstructField
         (
             const IOobject& fieldObject,
-            const PtrList<GeometricField<Type, fvPatchField, volMesh>>&
+            const UPtrList<GeometricField<Type, fvPatchField, volMesh>>&
         ) const;
 
         //- Read and reconstruct volume field
@@ -195,7 +195,7 @@ public:
         reconstructField
         (
             const IOobject& fieldObject,
-            const PtrList<GeometricField<Type, fvsPatchField, surfaceMesh>>&
+            const UPtrList<GeometricField<Type, fvsPatchField, surfaceMesh>>&
         ) const;
 
         //- Read and reconstruct surface field
@@ -269,7 +269,7 @@ public:
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 #ifdef NoRepository
-    #include "fvFieldReconstructorTemplates.C"
+    #include "fvFieldReconstructor.txx"
 #endif
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/parallel/reconstruct/reconstruct/fvFieldReconstructor.C b/src/parallel/reconstruct/reconstruct/fvFieldReconstructor.cxx
similarity index 95%
rename from src/parallel/reconstruct/reconstruct/fvFieldReconstructor.C
rename to src/parallel/reconstruct/reconstruct/fvFieldReconstructor.cxx
index a4d3a54365..2db28ef2de 100644
--- a/src/parallel/reconstruct/reconstruct/fvFieldReconstructor.C
+++ b/src/parallel/reconstruct/reconstruct/fvFieldReconstructor.cxx
@@ -40,10 +40,10 @@ int Foam::fvFieldReconstructor::verbose_ = 1;
 Foam::fvFieldReconstructor::fvFieldReconstructor
 (
     fvMesh& mesh,
-    const PtrList<fvMesh>& procMeshes,
-    const PtrList<labelIOList>& faceProcAddressing,
-    const PtrList<labelIOList>& cellProcAddressing,
-    const PtrList<labelIOList>& boundaryProcAddressing
+    const UPtrList<fvMesh>& procMeshes,
+    const UPtrList<labelIOList>& faceProcAddressing,
+    const UPtrList<labelIOList>& cellProcAddressing,
+    const UPtrList<labelIOList>& boundaryProcAddressing
 )
 :
     mesh_(mesh),
diff --git a/src/parallel/reconstruct/reconstruct/fvFieldReconstructorTemplates.C b/src/parallel/reconstruct/reconstruct/fvFieldReconstructor.txx
similarity index 98%
rename from src/parallel/reconstruct/reconstruct/fvFieldReconstructorTemplates.C
rename to src/parallel/reconstruct/reconstruct/fvFieldReconstructor.txx
index 1549abe4e7..cec57bf55f 100644
--- a/src/parallel/reconstruct/reconstruct/fvFieldReconstructorTemplates.C
+++ b/src/parallel/reconstruct/reconstruct/fvFieldReconstructor.txx
@@ -40,7 +40,7 @@ Foam::tmp<Foam::DimensionedField<Type, Foam::volMesh>>
 Foam::fvFieldReconstructor::reconstructField
 (
     const IOobject& fieldObject,
-    const PtrList<DimensionedField<Type, volMesh>>& procFields
+    const UPtrList<DimensionedField<Type, volMesh>>& procFields
 ) const
 {
     // Create the internalField
@@ -48,7 +48,7 @@ Foam::fvFieldReconstructor::reconstructField
 
     forAll(procMeshes_, proci)
     {
-        const DimensionedField<Type, volMesh>& procField = procFields[proci];
+        const auto& procField = procFields[proci];
 
         // Set the cell values in the reconstructed field
         internalField.rmap
@@ -77,7 +77,7 @@ Foam::tmp<Foam::GeometricField<Type, Foam::fvPatchField, Foam::volMesh>>
 Foam::fvFieldReconstructor::reconstructField
 (
     const IOobject& fieldObject,
-    const PtrList<GeometricField<Type, fvPatchField, volMesh>>& procFields
+    const UPtrList<GeometricField<Type, fvPatchField, volMesh>>& procFields
 ) const
 {
     // Create the internalField
@@ -255,7 +255,7 @@ Foam::tmp<Foam::GeometricField<Type, Foam::fvsPatchField, Foam::surfaceMesh>>
 Foam::fvFieldReconstructor::reconstructField
 (
     const IOobject& fieldObject,
-    const PtrList<GeometricField<Type, fvsPatchField, surfaceMesh>>& procFields
+    const UPtrList<GeometricField<Type, fvsPatchField, surfaceMesh>>& procFields
 ) const
 {
     // Create the internalField
diff --git a/src/parallel/reconstruct/reconstruct/lagrangianReconstructor.H b/src/parallel/reconstruct/reconstruct/lagrangianReconstructor.H
index 05a9c9a682..1ffb7136f2 100644
--- a/src/parallel/reconstruct/reconstruct/lagrangianReconstructor.H
+++ b/src/parallel/reconstruct/reconstruct/lagrangianReconstructor.H
@@ -31,8 +31,8 @@ Description
     Reconstructor for lagrangian positions and fields
 
 SourceFiles
-    lagrangianReconstructor.C
-    lagrangianReconstructorTemplates.C
+    lagrangianReconstructor.cxx
+    lagrangianReconstructor.txx
 
 \*---------------------------------------------------------------------------*/
 
@@ -59,16 +59,16 @@ class lagrangianReconstructor
     // Private Data
 
         //- Mesh reference
-        const fvMesh& mesh_;
+        const polyMesh& mesh_;
 
         //- List of processor meshes
-        const PtrList<fvMesh>& procMeshes_;
+        const UPtrList<fvMesh>& procMeshes_;
 
         //- List of processor face addressing lists
-        const PtrList<labelIOList>& faceProcAddressing_;
+        const UPtrList<labelIOList>& faceProcAddressing_;
 
         //- List of processor cell addressing lists
-        const PtrList<labelIOList>& cellProcAddressing_;
+        const UPtrList<labelIOList>& cellProcAddressing_;
 
 
     // Private Member Functions
@@ -93,10 +93,10 @@ public:
         //- Construct from components
         lagrangianReconstructor
         (
-            const fvMesh& mesh,
-            const PtrList<fvMesh>& procMeshes,
-            const PtrList<labelIOList>& faceProcAddressing,
-            const PtrList<labelIOList>& cellProcAddressing
+            const polyMesh& mesh,
+            const UPtrList<fvMesh>& procMeshes,
+            const UPtrList<labelIOList>& faceProcAddressing,
+            const UPtrList<labelIOList>& cellProcAddressing
         );
 
 
@@ -166,7 +166,7 @@ public:
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 #ifdef NoRepository
-    #include "lagrangianReconstructorTemplates.C"
+    #include "lagrangianReconstructor.txx"
 #endif
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/parallel/reconstruct/reconstruct/lagrangianReconstructor.C b/src/parallel/reconstruct/reconstruct/lagrangianReconstructor.cxx
similarity index 97%
rename from src/parallel/reconstruct/reconstruct/lagrangianReconstructor.C
rename to src/parallel/reconstruct/reconstruct/lagrangianReconstructor.cxx
index 508110e840..dafa4ee78d 100644
--- a/src/parallel/reconstruct/reconstruct/lagrangianReconstructor.C
+++ b/src/parallel/reconstruct/reconstruct/lagrangianReconstructor.cxx
@@ -38,10 +38,10 @@ int Foam::lagrangianReconstructor::verbose_ = 1;
 
 Foam::lagrangianReconstructor::lagrangianReconstructor
 (
-    const fvMesh& mesh,
-    const PtrList<fvMesh>& procMeshes,
-    const PtrList<labelIOList>& faceProcAddressing,
-    const PtrList<labelIOList>& cellProcAddressing
+    const polyMesh& mesh,
+    const UPtrList<fvMesh>& procMeshes,
+    const UPtrList<labelIOList>& faceProcAddressing,
+    const UPtrList<labelIOList>& cellProcAddressing
 )
 :
     mesh_(mesh),
diff --git a/src/parallel/reconstruct/reconstruct/lagrangianReconstructorTemplates.C b/src/parallel/reconstruct/reconstruct/lagrangianReconstructor.txx
similarity index 100%
rename from src/parallel/reconstruct/reconstruct/lagrangianReconstructorTemplates.C
rename to src/parallel/reconstruct/reconstruct/lagrangianReconstructor.txx
diff --git a/src/parallel/reconstruct/reconstruct/passivePositionParticleCloud.H b/src/parallel/reconstruct/reconstruct/passivePositionParticleCloud.H
index a864a15c3a..dfb765270d 100644
--- a/src/parallel/reconstruct/reconstruct/passivePositionParticleCloud.H
+++ b/src/parallel/reconstruct/reconstruct/passivePositionParticleCloud.H
@@ -30,7 +30,7 @@ Description
     A Cloud of passive particles
 
 SourceFiles
-    passivePositionParticleCloud.C
+    passivePositionParticleCloud.cxx
 
 \*---------------------------------------------------------------------------*/
 
@@ -79,7 +79,7 @@ public:
         passivePositionParticleCloud
         (
             const polyMesh& mesh,
-            const Foam::zero,
+            Foam::zero,
             const word& cloudName = cloud::defaultName
         )
         :
diff --git a/src/parallel/reconstruct/reconstruct/passivePositionParticleCloud.C b/src/parallel/reconstruct/reconstruct/passivePositionParticleCloud.cxx
similarity index 100%
rename from src/parallel/reconstruct/reconstruct/passivePositionParticleCloud.C
rename to src/parallel/reconstruct/reconstruct/passivePositionParticleCloud.cxx
diff --git a/src/parallel/reconstruct/reconstruct/pointFieldReconstructor.H b/src/parallel/reconstruct/reconstruct/pointFieldReconstructor.H
index 3cac39a3c6..51fbb83430 100644
--- a/src/parallel/reconstruct/reconstruct/pointFieldReconstructor.H
+++ b/src/parallel/reconstruct/reconstruct/pointFieldReconstructor.H
@@ -31,8 +31,8 @@ Description
     Point field reconstructor.
 
 SourceFiles
-    pointFieldReconstructor.C
-    pointFieldReconstructorTemplates.C
+    pointFieldReconstructor.cxx
+    pointFieldReconstructor.txx
 
 \*---------------------------------------------------------------------------*/
 
@@ -41,7 +41,7 @@ SourceFiles
 
 #include "pointMesh.H"
 #include "pointFields.H"
-#include "pointPatchFieldMapperPatchRef.H"
+#include "pointPatchFieldMapper.H"
 #include "IOobjectList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -61,13 +61,13 @@ class pointFieldReconstructor
         const pointMesh& mesh_;
 
         //- List of processor meshes
-        const PtrList<pointMesh>& procMeshes_;
+        const UPtrList<pointMesh>& procMeshes_;
 
         //- List of processor point addressing lists
-        const PtrList<labelIOList>& pointProcAddressing_;
+        const UPtrList<labelIOList>& pointProcAddressing_;
 
         //- List of processor boundary addressing lists
-        const PtrList<labelIOList>& boundaryProcAddressing_;
+        const UPtrList<labelIOList>& boundaryProcAddressing_;
 
         //- Point patch addressing
         labelListListList patchPointAddressing_;
@@ -100,7 +100,7 @@ public:
             // Constructors
 
                 //- Construct given size
-                pointPatchFieldReconstructor(const label size)
+                explicit pointPatchFieldReconstructor(const label size)
                 :
                     size_(size)
                 {}
@@ -108,22 +108,22 @@ public:
 
             // Member functions
 
-                label size() const
+                label size() const noexcept
                 {
                     return size_;
                 }
 
-                bool direct() const
+                bool direct() const noexcept
                 {
                     return true;
                 }
 
-                bool hasUnmapped() const
+                bool hasUnmapped() const noexcept
                 {
                     return false;
                 }
 
-                const labelUList& directAddressing() const
+                const labelUList& directAddressing() const noexcept
                 {
                     return labelUList::null();
                 }
@@ -142,9 +142,9 @@ public:
         pointFieldReconstructor
         (
             const pointMesh& mesh,
-            const PtrList<pointMesh>& procMeshes,
-            const PtrList<labelIOList>& pointProcAddressing,
-            const PtrList<labelIOList>& boundaryProcAddressing
+            const UPtrList<pointMesh>& procMeshes,
+            const UPtrList<labelIOList>& pointProcAddressing,
+            const UPtrList<labelIOList>& boundaryProcAddressing
         );
 
 
@@ -163,7 +163,7 @@ public:
         reconstructField
         (
             const IOobject& fieldObject,
-            const PtrList<GeometricField<Type, pointPatchField, pointMesh>>&
+            const UPtrList<GeometricField<Type, pointPatchField, pointMesh>>&
         ) const;
 
 
@@ -204,7 +204,7 @@ public:
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 #ifdef NoRepository
-    #include "pointFieldReconstructorTemplates.C"
+    #include "pointFieldReconstructor.txx"
 #endif
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/parallel/reconstruct/reconstruct/pointFieldReconstructor.C b/src/parallel/reconstruct/reconstruct/pointFieldReconstructor.cxx
similarity index 76%
rename from src/parallel/reconstruct/reconstruct/pointFieldReconstructor.C
rename to src/parallel/reconstruct/reconstruct/pointFieldReconstructor.cxx
index 05a7fe260e..e9d709b72b 100644
--- a/src/parallel/reconstruct/reconstruct/pointFieldReconstructor.C
+++ b/src/parallel/reconstruct/reconstruct/pointFieldReconstructor.cxx
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2015 OpenFOAM Foundation
-    Copyright (C) 2022 OpenCFD Ltd.
+    Copyright (C) 2022-2025 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -39,9 +39,9 @@ int Foam::pointFieldReconstructor::verbose_ = 1;
 Foam::pointFieldReconstructor::pointFieldReconstructor
 (
     const pointMesh& mesh,
-    const PtrList<pointMesh>& procMeshes,
-    const PtrList<labelIOList>& pointProcAddressing,
-    const PtrList<labelIOList>& boundaryProcAddressing
+    const UPtrList<pointMesh>& procMeshes,
+    const UPtrList<labelIOList>& pointProcAddressing,
+    const UPtrList<labelIOList>& boundaryProcAddressing
 )
 :
     mesh_(mesh),
@@ -59,14 +59,14 @@ Foam::pointFieldReconstructor::pointFieldReconstructor
     {
         const pointMesh& procMesh = procMeshes_[proci];
 
-        patchPointAddressing_[proci].setSize(procMesh.boundary().size());
+        patchPointAddressing_[proci].resize(procMesh.boundary().size());
 
         forAll(procMesh.boundary(), patchi)
         {
             if (boundaryProcAddressing_[proci][patchi] >= 0)
             {
                 labelList& procPatchAddr = patchPointAddressing_[proci][patchi];
-                procPatchAddr.setSize(procMesh.boundary()[patchi].size(), -1);
+                procPatchAddr.resize(procMesh.boundary()[patchi].size(), -1);
 
                 const labelList& patchPointLabels =
                     mesh_.boundary()[boundaryProcAddressing_[proci][patchi]]
@@ -90,7 +90,7 @@ Foam::pointFieldReconstructor::pointFieldReconstructor
                         ];
                 }
 
-                if (procPatchAddr.size() && min(procPatchAddr) < 0)
+                if (procPatchAddr.contains(-1))
                 {
                     FatalErrorInFunction
                         << "Incomplete patch point addressing"
@@ -112,11 +112,23 @@ Foam::label Foam::pointFieldReconstructor::reconstructAllFields
 {
     label nTotal = 0;
 
-    nTotal += reconstructPointFields<scalar>(objects, selected);
-    nTotal += reconstructPointFields<vector>(objects, selected);
-    nTotal += reconstructPointFields<symmTensor>(objects, selected);
-    nTotal += reconstructPointFields<sphericalTensor>(objects, selected);
-    nTotal += reconstructPointFields<tensor>(objects, selected);
+    do
+    {
+        #undef  doLocalCode
+        #define doLocalCode(Method)                                           \
+        {                                                                     \
+            nTotal += this->Method <scalar> (objects, selected);              \
+            nTotal += this->Method <vector> (objects, selected);              \
+            nTotal += this->Method <sphericalTensor> (objects, selected);     \
+            nTotal += this->Method <symmTensor> (objects, selected);          \
+            nTotal += this->Method <tensor> (objects, selected);              \
+        }
+
+        doLocalCode(reconstructPointFields);
+
+        #undef doLocalCode
+    }
+    while (false);
 
     return nTotal;
 }
diff --git a/src/parallel/reconstruct/reconstruct/pointFieldReconstructorTemplates.C b/src/parallel/reconstruct/reconstruct/pointFieldReconstructor.txx
similarity index 95%
rename from src/parallel/reconstruct/reconstruct/pointFieldReconstructorTemplates.C
rename to src/parallel/reconstruct/reconstruct/pointFieldReconstructor.txx
index bc7b03167a..f62cb0a08e 100644
--- a/src/parallel/reconstruct/reconstruct/pointFieldReconstructorTemplates.C
+++ b/src/parallel/reconstruct/reconstruct/pointFieldReconstructor.txx
@@ -35,16 +35,17 @@ Foam::tmp<Foam::GeometricField<Type, Foam::pointPatchField, Foam::pointMesh>>
 Foam::pointFieldReconstructor::reconstructField
 (
     const IOobject& fieldObject,
-    const PtrList<GeometricField<Type, pointPatchField, pointMesh>>& procFields
+    const UPtrList<GeometricField<Type, pointPatchField, pointMesh>>& procFields
 ) const
 {
     typedef GeometricField<Type, pointPatchField, pointMesh> fieldType;
+    typedef pointPatchField<Type> patchFieldType;
 
     // Create the internalField
     Field<Type> internalField(mesh_.size());
 
     // Create the patch fields
-    PtrList<pointPatchField<Type>> patchFields(mesh_.boundary().size());
+    PtrList<patchFieldType> patchFields(mesh_.boundary().size());
 
 
     forAll(procMeshes_, proci)
@@ -75,11 +76,11 @@ Foam::pointFieldReconstructor::reconstructField
                     patchFields.set
                     (
                         curBPatch,
-                        pointPatchField<Type>::New
+                        patchFieldType::New
                         (
                             procField.boundaryField()[patchi],
                             mesh_.boundary()[curBPatch],
-                            pointPatchField<Type>::Internal::null(),
+                            patchFieldType::Internal::null(),
                             pointPatchFieldReconstructor
                             (
                                 mesh_.boundary()[curBPatch].size()
diff --git a/src/parallel/reconstruct/reconstruct/processorMeshes.H b/src/parallel/reconstruct/reconstruct/processorMeshes.H
index d8da977c73..1abe940826 100644
--- a/src/parallel/reconstruct/reconstruct/processorMeshes.H
+++ b/src/parallel/reconstruct/reconstruct/processorMeshes.H
@@ -31,7 +31,7 @@ Description
     Container for processor mesh addressing.
 
 SourceFiles
-    processorMeshes.C
+    processorMeshes.cxx
 
 \*---------------------------------------------------------------------------*/
 
@@ -40,7 +40,6 @@ SourceFiles
 
 #include "PtrList.H"
 #include "fvMesh.H"
-#include "IOobjectList.H"
 #include "labelIOList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -56,10 +55,11 @@ class processorMeshes
 {
     // Private Data
 
+        //- The (volume) mesh-region name
         const word meshName_;
 
         //- Processor databases
-        PtrList<Time>& databases_;
+        const UPtrList<Time>& databases_;
 
         //- List of processor meshes
         PtrList<fvMesh> meshes_;
@@ -76,14 +76,11 @@ class processorMeshes
         //- List of processor boundary addressing lists
         PtrList<labelIOList> boundaryProcAddressing_;
 
+        //- List of pointMesh processor meshes
+        PtrList<pointMesh> pMeshes_;
 
-        // pointMesh
-
-            //- List of processor meshes
-            PtrList<pointMesh> pMeshes_;
-
-            //- List of processor boundary addressing lists for pointMeshes
-            PtrList<labelIOList> pBoundaryProcAddressing_;
+        //- List of processor boundary addressing lists for pointMeshes
+        PtrList<labelIOList> pBoundaryProcAddressing_;
 
 
     // Private Member Functions
@@ -107,22 +104,30 @@ public:
     // Constructors
 
         //- Construct from components
-        processorMeshes(PtrList<Time>& databases, const word& meshName);
+        processorMeshes(const UPtrList<Time>& databases, const word& meshName);
 
 
     // Member Functions
 
-        //- Update the meshes based on the mesh files saved in time directories
+        //- Update meshes based on the mesh files saved in time directories
         polyMesh::readUpdateState readUpdate();
 
         //- Reconstruct point position after motion in parallel
         void reconstructPoints(fvMesh&);
 
+        //- The (volume) mesh-region name
+        const word& name() const noexcept { return meshName_; }
+
+        //- The number of processors used
+        label nProcs() const noexcept { return databases_.size(); }
+
+        //- The processor meshes
         const PtrList<fvMesh>& meshes() const noexcept
         {
             return meshes_;
         }
 
+        //- The processor meshes
         PtrList<fvMesh>& meshes() noexcept
         {
             return meshes_;
@@ -149,18 +154,17 @@ public:
         }
 
 
-        // pointMesh
+        //- The processor point meshes
+        const PtrList<pointMesh>& pointMeshes() const noexcept
+        {
+            return pMeshes_;
+        }
 
-            const PtrList<pointMesh>& pointMeshes() const noexcept
-            {
-                return pMeshes_;
-            }
-
-            const PtrList<labelIOList>& pointMeshBoundaryProcAddressing()
-            const noexcept
-            {
-                return pBoundaryProcAddressing_;
-            }
+        const PtrList<labelIOList>& pointMeshBoundaryProcAddressing()
+        const noexcept
+        {
+            return pBoundaryProcAddressing_;
+        }
 
 
         //- Helper: remove all procAddressing files from mesh instance
diff --git a/src/parallel/reconstruct/reconstruct/processorMeshes.C b/src/parallel/reconstruct/reconstruct/processorMeshes.cxx
similarity index 80%
rename from src/parallel/reconstruct/reconstruct/processorMeshes.C
rename to src/parallel/reconstruct/reconstruct/processorMeshes.cxx
index 1eb12aa09c..f8495ffb86 100644
--- a/src/parallel/reconstruct/reconstruct/processorMeshes.C
+++ b/src/parallel/reconstruct/reconstruct/processorMeshes.cxx
@@ -30,8 +30,8 @@ License
 #include "Time.H"
 #include "IndirectList.H"
 #include "primitiveMesh.H"
-#include "OSspecific.H"
 #include "pointMesh.H"
+#include "OSspecific.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -47,16 +47,19 @@ void Foam::processorMeshes::read()
 {
     // Make sure to clear (and hence unregister) any previously loaded meshes
     // and fields
-    pBoundaryProcAddressing_.free();
-    pMeshes_.free();
 
-    boundaryProcAddressing_.free();
-    cellProcAddressing_.free();
-    faceProcAddressing_.free();
-    pointProcAddressing_.free();
-    meshes_.free();
+    const label numProc = databases_.size();
 
-    forAll(databases_, proci)
+    pBoundaryProcAddressing_.resize_null(numProc);
+    pMeshes_.resize_null(numProc);
+
+    boundaryProcAddressing_.resize_null(numProc);
+    cellProcAddressing_.resize_null(numProc);
+    faceProcAddressing_.resize_null(numProc);
+    pointProcAddressing_.resize_null(numProc);
+    meshes_.resize_null(numProc);
+
+    for (label proci = 0; proci < numProc; ++proci)
     {
         meshes_.emplace_set
         (
@@ -104,11 +107,7 @@ void Foam::processorMeshes::read()
         pMeshes_.set
         (
             proci,
-            new pointMesh
-            (
-                meshes_[proci],
-                IOobject::READ_IF_PRESENT
-            )
+            new pointMesh(meshes_[proci], IOobjectOption::READ_IF_PRESENT)
         );
 
         pBoundaryProcAddressing_.set
@@ -122,9 +121,9 @@ void Foam::processorMeshes::read()
                     meshes_[proci].facesInstance(),
                     polyMesh::meshSubDir/pointMesh::meshSubDir,
                     pMeshes_[proci].thisDb(),
-                    IOobject::READ_IF_PRESENT,
-                    IOobject::NO_WRITE,
-                    IOobject::NO_REGISTER
+                    IOobjectOption::READ_IF_PRESENT,
+                    IOobjectOption::NO_WRITE,
+                    IOobjectOption::NO_REGISTER
                 ),
                 boundaryProcAddressing_[proci]
             )
@@ -137,19 +136,12 @@ void Foam::processorMeshes::read()
 
 Foam::processorMeshes::processorMeshes
 (
-    PtrList<Time>& databases,
+    const UPtrList<Time>& databases,
     const word& meshName
 )
 :
-    meshName_(meshName),
-    databases_(databases),
-    meshes_(databases.size()),
-    pointProcAddressing_(databases.size()),
-    faceProcAddressing_(databases.size()),
-    cellProcAddressing_(databases.size()),
-    boundaryProcAddressing_(databases.size()),
-    pMeshes_(databases.size()),
-    pBoundaryProcAddressing_(databases.size())
+    meshName_(meshName.empty() ? polyMesh::defaultRegion : meshName),
+    databases_(databases)
 {
     read();
 }
@@ -161,7 +153,9 @@ Foam::polyMesh::readUpdateState Foam::processorMeshes::readUpdate()
 {
     polyMesh::readUpdateState stat = polyMesh::UNCHANGED;
 
-    forAll(databases_, proci)
+    const label numProc = meshes_.size();
+
+    for (label proci = 0; proci < numProc; ++proci)
     {
         // Check if any new meshes need to be read.
         polyMesh::readUpdateState procStat = meshes_[proci].readUpdate();
@@ -210,43 +204,34 @@ Foam::polyMesh::readUpdateState Foam::processorMeshes::readUpdate()
 
 void Foam::processorMeshes::reconstructPoints(fvMesh& mesh)
 {
-    // Read the field for all the processors
-    PtrList<pointIOField> procsPoints(meshes_.size());
-
-    forAll(meshes_, proci)
-    {
-        procsPoints.set
-        (
-            proci,
-            new pointIOField
-            (
-                IOobject
-                (
-                    "points",
-                    meshes_[proci].time().timeName(),
-                    polyMesh::meshSubDir,
-                    meshes_[proci].thisDb(),
-                    IOobject::MUST_READ,
-                    IOobject::NO_WRITE,
-                    IOobject::NO_REGISTER
-                )
-            )
-        );
-    }
-
-    // Create the new points
+    // The new points
     vectorField newPoints(mesh.nPoints());
 
-    forAll(meshes_, proci)
-    {
-        const vectorField& procPoints = procsPoints[proci];
+    // Read the "points" field for each processor
+    const label numProc = meshes_.size();
 
-        const labelList& pointProcAddr = pointProcAddressing_[proci];
+    for (label proci = 0; proci < numProc; ++proci)
+    {
+        pointIOField procPoints
+        (
+            IOobject
+            (
+                "points",
+                meshes_[proci].time().timeName(),
+                polyMesh::meshSubDir,
+                meshes_[proci].thisDb(),
+                IOobject::MUST_READ,
+                IOobject::NO_WRITE,
+                IOobject::NO_REGISTER
+            )
+        );
+
+        const labelUList& pointProcAddr = pointProcAddressing_[proci];
 
         if (pointProcAddr.size() != procPoints.size())
         {
             FatalErrorInFunction
-                << "problem :"
+                << "problem [proc=" << proci << "] :"
                 << " pointProcAddr:" << pointProcAddr.size()
                 << " procPoints:" << procPoints.size()
                 << abort(FatalError);