diff --git a/src/thermophysicalModels/chemistryModel/chemistryModel/chemistryModel.H b/src/thermophysicalModels/chemistryModel/chemistryModel/chemistryModel.H
index ac8d7ff5c6..512f606e5f 100644
--- a/src/thermophysicalModels/chemistryModel/chemistryModel/chemistryModel.H
+++ b/src/thermophysicalModels/chemistryModel/chemistryModel/chemistryModel.H
@@ -105,6 +105,23 @@ private:
         //- Disallow default bitwise assignment
         void operator=(const chemistryModel&);
 
+protected:
+
+    // Protected Member Functions
+
+        //- Write access to chemical source terms
+        //  (eg, for multi-chemistry model)
+        PtrList<scalarField>& RR()
+        {
+            return RR_;
+        }
+
+        //- Return the latest estimation of integration step
+        //  (eg, for multi-chemistry model)
+        scalarField& deltaTChem()
+        {
+            return deltaTChem_;
+        }
 
 public: