diff --git a/etc/config.csh/mpi b/etc/config.csh/mpi
index 4942b58efd..48126fde7a 100644
--- a/etc/config.csh/mpi
+++ b/etc/config.csh/mpi
@@ -379,29 +379,18 @@ endsw
 
 
 #------------------------------------------------------------------------------
-# Final
 
-# A real (non-dummy) MPI
-if ( "$FOAM_MPI" != dummy ) then
-    if ($?FOAM_VERBOSE && $?prompt) then
-        echo "Using mpi type : $WM_MPLIB"
-        echo "      FOAM_MPI : $FOAM_MPI"
-        if ( "${MPI_ARCH_PATH}" == "" ) then
-            echo "        prefix : unset"
-        else
-            echo "        prefix : $MPI_ARCH_PATH"
-        endif
+# Report
+if ($?FOAM_VERBOSE && $?prompt) then
+    echo "Using mpi type : $WM_MPLIB"
+    echo "      FOAM_MPI : $FOAM_MPI"
+    if ( "${MPI_ARCH_PATH}" == "" ) then
+        echo "        prefix : unset"
+    else
+        echo "        prefix : $MPI_ARCH_PATH"
     endif
-
-    # OpenFOAM library interface to (non-dummy) MPI
-    if ( $?FOAM_EXT_LIBBIN ) then
-        # External libraries (can be unset)
-        _foamAddLib "${FOAM_EXT_LIBBIN}/${FOAM_MPI}"
-    endif
-    _foamAddLib "${FOAM_LIBBIN}/${FOAM_MPI}"
 endif
 
-
 # Cleanup
 unset _foamMpiPrefixDir _foamMpiWarning _foamMpiVersion
 
diff --git a/etc/config.csh/settings b/etc/config.csh/settings
index 76a30a8571..4919f0092a 100644
--- a/etc/config.csh/settings
+++ b/etc/config.csh/settings
@@ -6,7 +6,7 @@
 #    \\/     M anipulation  |
 #------------------------------------------------------------------------------
 #     Copyright (C) 2011-2016 OpenFOAM Foundation
-#     Copyright (C) 2016-2020 OpenCFD Ltd.
+#     Copyright (C) 2016-2021 OpenCFD Ltd.
 #------------------------------------------------------------------------------
 # License
 #     This file is part of OpenFOAM, distributed under GPL-3.0-or-later.
@@ -177,14 +177,10 @@ _foamAddLib  "$FOAM_LIBBIN/dummy"
 # External (ThirdParty) libraries. Also allowed to be unset
 if ( -d "$WM_THIRD_PARTY_DIR" ) then
     setenv FOAM_EXT_LIBBIN "$WM_THIRD_PARTY_DIR/platforms/$WM_ARCH$WM_COMPILER$WM_PRECISION_OPTION$WM_LABEL_OPTION/lib"
-    _foamAddLib "$FOAM_EXT_LIBBIN"
 else
     unsetenv FOAM_EXT_LIBBIN
 endif
 
-# OpenFOAM libraries (user, group, standard)
-_foamAddLib  "${FOAM_USER_LIBBIN}:${FOAM_SITE_LIBBIN}:${FOAM_LIBBIN}"
-
 
 #------------------------------------------------------------------------------
 
diff --git a/etc/config.csh/setup b/etc/config.csh/setup
index a852c9461d..49d5d4ad5d 100644
--- a/etc/config.csh/setup
+++ b/etc/config.csh/setup
@@ -133,6 +133,9 @@ while ( $#argv > 0 )
     shift
 end
 
+
+#----------------------------------------------------------------------------
+
 # Verify FOAM_CONFIG_ETC (from calling environment or from prefs)
 if ( $?FOAM_CONFIG_ETC ) then
     if ( "$FOAM_CONFIG_ETC" == "etc" || "$FOAM_CONFIG_ETC" == "$WM_PROJECT_DIR/etc" ) then
@@ -143,8 +146,8 @@ endif
 
 
 # Clean standard environment variables (PATH, MANPATH, LD_LIBRARY_PATH)
-# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-# Prevent local variables from shadowing setenv variables
+# - avoid local variables shadowing setenv variables
+
 unset PATH MANPATH LD_LIBRARY_PATH DYLD_LIBRARY_PATH
 if (! $?MANPATH ) setenv MANPATH
 if (! $?LD_LIBRARY_PATH ) setenv LD_LIBRARY_PATH
@@ -153,12 +156,11 @@ _foamClean PATH "$foamOldDirs"
 _foamClean MANPATH "$foamOldDirs"
 _foamClean LD_LIBRARY_PATH "$foamOldDirs"
 
-# Setup for OpenFOAM compilation etc
-# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-_foamEtc -config  settings
 
-# Setup for third-party packages
-# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+#------------------------------------------------------------------------------
+# Base setup (OpenFOAM compilation), MPI and third-party packages
+
+_foamEtc -config  settings
 _foamEtc -config  mpi
 _foamEtc -config  paraview -- "$FOAM_SETTINGS"  # Pass through for evaluation
 _foamEtc -config  vtk
@@ -166,6 +168,30 @@ _foamEtc -config  adios2
 _foamEtc -config  CGAL
 _foamEtc -config  FFTW
 
+if (! $?FOAM_MPI ) then
+    setenv FOAM_MPI dummy  # Fallback value
+endif
+
+# Finalize library paths
+# ~~~~~~~~~~~~~~~~~~~~~~
+
+# ThirdParty serial and mpi-specific libraries
+if ( $?FOAM_EXT_LIBBIN ) then
+    _foamAddLib "${FOAM_EXT_LIBBIN}"
+    if ( "$FOAM_MPI" != dummy ) then
+        _foamAddLib "${FOAM_EXT_LIBBIN}/${FOAM_MPI}"
+    endif
+endif
+
+# OpenFOAM serial and mpi-specific libraries
+_foamAddLib  "$FOAM_LIBBIN"
+if ( "$FOAM_MPI" != dummy ) then
+    _foamAddLib "${FOAM_LIBBIN}/${FOAM_MPI}"
+endif
+
+# OpenFOAM user, group libraries
+_foamAddLib  "${FOAM_USER_LIBBIN}:${FOAM_SITE_LIBBIN}"
+
 if ( -d "$WM_PROJECT_DIR/doc/man1" ) then
     _foamAddMan "$WM_PROJECT_DIR/doc"
 endif
@@ -177,8 +203,9 @@ if ($?prompt) then
 endif
 
 
-# Clean environment paths again. Only remove duplicates
-# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+#------------------------------------------------------------------------------
+
+# Remove duplicates from environment paths
 
 _foamClean PATH
 _foamClean MANPATH
diff --git a/etc/config.sh/mpi b/etc/config.sh/mpi
index 90885f6423..ed38419271 100644
--- a/etc/config.sh/mpi
+++ b/etc/config.sh/mpi
@@ -434,30 +434,14 @@ esac
 # Ensure MPI_ARCH_PATH is marked for export
 [ -n "$MPI_ARCH_PATH" ] && export MPI_ARCH_PATH
 
-
-# A real (non-dummy) MPI
-if [ "$FOAM_MPI" != dummy ]
+# Report
+if [ -n "$FOAM_VERBOSE" ] && [ -n "$PS1" ]
 then
-    if [ -n "$FOAM_VERBOSE" ] && [ -n "$PS1" ]
-    then
-        echo "Using mpi type : $WM_MPLIB" 1>&2
-        echo "      FOAM_MPI : $FOAM_MPI" 1>&2
-        echo "        prefix : ${MPI_ARCH_PATH:-unset}" 1>&2
-    fi
-
-    # OpenFOAM library interface to (non-dummy) MPI
-    if command -v _foamAddLib >/dev/null
-    then
-        if [ -n "$FOAM_EXT_LIBBIN" ]
-        then
-            # External libraries (can be unset)
-            _foamAddLib "$FOAM_EXT_LIBBIN/$FOAM_MPI"
-        fi
-        _foamAddLib "$FOAM_LIBBIN/$FOAM_MPI"
-    fi
+    echo "Using mpi type : $WM_MPLIB" 1>&2
+    echo "      FOAM_MPI : $FOAM_MPI" 1>&2
+    echo "        prefix : ${MPI_ARCH_PATH:-[unset]}" 1>&2
 fi
 
-
 # Cleanup
 unset _foamMpiPrefixDir _foamMpiVersion _foamMpiWarning
 
diff --git a/etc/config.sh/settings b/etc/config.sh/settings
index f3a0d11137..7a69e91e52 100644
--- a/etc/config.sh/settings
+++ b/etc/config.sh/settings
@@ -6,7 +6,7 @@
 #    \\/     M anipulation  |
 #------------------------------------------------------------------------------
 #     Copyright (C) 2011-2016 OpenFOAM Foundation
-#     Copyright (C) 2016-2020 OpenCFD Ltd.
+#     Copyright (C) 2016-2021 OpenCFD Ltd.
 #------------------------------------------------------------------------------
 # License
 #     This file is part of OpenFOAM, distributed under GPL-3.0-or-later.
@@ -178,14 +178,10 @@ _foamAddLib  "$FOAM_LIBBIN/dummy"
 if [ -d "$WM_THIRD_PARTY_DIR" ]
 then
     export FOAM_EXT_LIBBIN="$WM_THIRD_PARTY_DIR/platforms/$WM_ARCH$WM_COMPILER$WM_PRECISION_OPTION$WM_LABEL_OPTION/lib"
-    _foamAddLib "$FOAM_EXT_LIBBIN"
 else
     unset FOAM_EXT_LIBBIN
 fi
 
-# OpenFOAM libraries (user, group, standard)
-_foamAddLib  "$FOAM_USER_LIBBIN:$FOAM_SITE_LIBBIN:$FOAM_LIBBIN"
-
 
 #------------------------------------------------------------------------------
 
diff --git a/etc/config.sh/setup b/etc/config.sh/setup
index a5440df6f4..36ef8d63e9 100644
--- a/etc/config.sh/setup
+++ b/etc/config.sh/setup
@@ -181,19 +181,17 @@ else
 fi
 
 
-# Clean standard environment variables (PATH, MANPATH, LD_LIBRARY_PATH)
-# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+# Clean standard environment variables
+
 export PATH MANPATH LD_LIBRARY_PATH
 _foamClean PATH "$foamOldDirs"
 _foamClean MANPATH "$foamOldDirs"
 _foamClean LD_LIBRARY_PATH "$foamOldDirs"
 
-# Setup for OpenFOAM compilation etc
-# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-_foamEtc -config  settings
+#------------------------------------------------------------------------------
+# Base setup (OpenFOAM compilation), MPI and third-party packages
 
-# Setup for third-party packages
-# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+_foamEtc -config  settings
 _foamEtc -config  mpi
 _foamEtc -config  paraview -- "$@"  # Pass through for evaluation
 _foamEtc -config  vtk
@@ -202,6 +200,30 @@ _foamEtc -config  CGAL
 _foamEtc -config  scotch
 _foamEtc -config  FFTW
 
+
+# Finalize library paths
+# ~~~~~~~~~~~~~~~~~~~~~~
+
+# ThirdParty serial and mpi-specific libraries
+if [ -n "$FOAM_EXT_LIBBIN" ]
+then
+    _foamAddLib "$FOAM_EXT_LIBBIN"
+    if [ "${FOAM_MPI:-dummy}" != dummy ]
+    then
+        _foamAddLib "$FOAM_EXT_LIBBIN/$FOAM_MPI"
+    fi
+fi
+
+# OpenFOAM serial and mpi-specific libraries
+_foamAddLib "$FOAM_LIBBIN"
+if [ "${FOAM_MPI:-dummy}" != dummy ]
+then
+    _foamAddLib "$FOAM_LIBBIN/$FOAM_MPI"
+fi
+
+# OpenFOAM user, group libraries
+_foamAddLib  "$FOAM_USER_LIBBIN:$FOAM_SITE_LIBBIN"
+
 if [ -d "$WM_PROJECT_DIR/doc/man1" ]
 then
     _foamAddMan "$WM_PROJECT_DIR/doc"
@@ -215,8 +237,9 @@ then
 fi
 
 
-# Clean environment paths again. Only remove duplicates
-# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+#------------------------------------------------------------------------------
+
+# Remove duplicates from environment paths
 export PATH MANPATH LD_LIBRARY_PATH
 
 _foamClean PATH
@@ -229,7 +252,6 @@ then
     MANPATH="${MANPATH}:"
 fi
 
-
 # Cleanup temporary information
 # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~