diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/GAMGProcAgglomeration/GAMGProcAgglomeration.C b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/GAMGProcAgglomeration/GAMGProcAgglomeration.C
index 48512f5842..247f72fb50 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/GAMGProcAgglomeration/GAMGProcAgglomeration.C
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/GAMGProcAgglomeration/GAMGProcAgglomeration.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2013-2017 OpenFOAM Foundation
-    Copyright (C) 2021-2022 OpenCFD Ltd.
+    Copyright (C) 2021-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -380,7 +380,21 @@ Foam::autoPtr<Foam::GAMGProcAgglomeration> Foam::GAMGProcAgglomeration::New
 // * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
 Foam::GAMGProcAgglomeration::~GAMGProcAgglomeration()
-{}
+{
+    clearCommunicators();
+}
+
+
+// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
+
+void Foam::GAMGProcAgglomeration::clearCommunicators()
+{
+    forAllReverse(comms_, i)
+    {
+        UPstream::freeCommunicator(comms_[i]);
+    }
+    comms_.clear();
+}
 
 
 // ************************************************************************* //
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/GAMGProcAgglomeration/GAMGProcAgglomeration.H b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/GAMGProcAgglomeration/GAMGProcAgglomeration.H
index 999a474fc2..07381d98a1 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/GAMGProcAgglomeration/GAMGProcAgglomeration.H
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/GAMGProcAgglomeration/GAMGProcAgglomeration.H
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2013-2014 OpenFOAM Foundation
+    Copyright (C) 2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -34,19 +35,22 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef GAMGProcAgglomeration_H
-#define GAMGProcAgglomeration_H
+#ifndef Foam_GAMGProcAgglomeration_H
+#define Foam_GAMGProcAgglomeration_H
 
 #include "runTimeSelectionTables.H"
 #include "labelList.H"
+#include "DynamicList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
+// Forward Declarations
 class GAMGAgglomeration;
 class lduMesh;
+class lduPrimitiveMesh;
 
 /*---------------------------------------------------------------------------*\
                     Class GAMGProcAgglomeration Declaration
@@ -54,14 +58,17 @@ class lduMesh;
 
 class GAMGProcAgglomeration
 {
-
 protected:
 
-    // Protected data
+    // Protected Data
 
         //- Reference to agglomeration
         GAMGAgglomeration& agglom_;
 
+        //- Allocated communicators
+        DynamicList<label> comms_;
+
+
     // Protected Member Functions
 
         //- Debug: write agglomeration info
@@ -80,17 +87,8 @@ protected:
         //- Debug: calculate global cell-cells
         static labelListList globalCellCells(const lduMesh&);
 
-private:
-
-    // Private data
-
-    // Private Member Functions
-
-        //- No copy construct
-        GAMGProcAgglomeration(const GAMGProcAgglomeration&) = delete;
-
-        //- No copy assignment
-        void operator=(const GAMGProcAgglomeration&) = delete;
+        //- Clear/free allocated communicators
+        void clearCommunicators();
 
 
 public:
@@ -118,6 +116,13 @@ public:
         );
 
 
+    //- No copy construct
+    GAMGProcAgglomeration(const GAMGProcAgglomeration&) = delete;
+
+    //- No copy assignment
+    void operator=(const GAMGProcAgglomeration&) = delete;
+
+
     // Constructors
 
         //- Construct given agglomerator and controls
@@ -139,15 +144,14 @@ public:
         );
 
 
-    //- Destructor
+    //- Destructor. Clears allocated communicators
     virtual ~GAMGProcAgglomeration();
 
 
     // Member Functions
 
-        //- Modify agglomeration. Return true if modified
+        //- Modify agglomeration. \returns True if modified
         virtual bool agglomerate() = 0;
-
 };
 
 
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/eagerGAMGProcAgglomeration/eagerGAMGProcAgglomeration.C b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/eagerGAMGProcAgglomeration/eagerGAMGProcAgglomeration.C
index 3866554614..33139bb24c 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/eagerGAMGProcAgglomeration/eagerGAMGProcAgglomeration.C
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/eagerGAMGProcAgglomeration/eagerGAMGProcAgglomeration.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2013-2016 OpenFOAM Foundation
-    Copyright (C) 2020 OpenCFD Ltd.
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -60,14 +60,8 @@ Foam::eagerGAMGProcAgglomeration::eagerGAMGProcAgglomeration
 
 // * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
-Foam::eagerGAMGProcAgglomeration::
-~eagerGAMGProcAgglomeration()
-{
-    forAllReverse(comms_, i)
-    {
-        UPstream::freeCommunicator(comms_[i]);
-    }
-}
+Foam::eagerGAMGProcAgglomeration::~eagerGAMGProcAgglomeration()
+{}
 
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
@@ -122,9 +116,8 @@ bool Foam::eagerGAMGProcAgglomeration::agglomerate()
                         agglomProcIDs
                     );
 
-                    // Allocate a communicator for the processor-agglomerated
-                    // matrix
-                    comms_.append
+                    // Communicator for the processor-agglomerated matrix
+                    comms_.push_back
                     (
                         UPstream::allocateCommunicator
                         (
@@ -135,7 +128,7 @@ bool Foam::eagerGAMGProcAgglomeration::agglomerate()
 
                     // Use processor agglomeration maps to do the actual
                     // collecting.
-                    if (Pstream::myProcNo(levelComm) != -1)
+                    if (UPstream::myProcNo(levelComm) != -1)
                     {
                         GAMGProcAgglomeration::agglomerate
                         (
@@ -143,7 +136,7 @@ bool Foam::eagerGAMGProcAgglomeration::agglomerate()
                             procAgglomMap,
                             masterProcs,
                             agglomProcIDs,
-                            comms_.last()
+                            comms_.back()
                         );
                     }
                 }
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/eagerGAMGProcAgglomeration/eagerGAMGProcAgglomeration.H b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/eagerGAMGProcAgglomeration/eagerGAMGProcAgglomeration.H
index 784723e08b..48969a34cb 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/eagerGAMGProcAgglomeration/eagerGAMGProcAgglomeration.H
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/eagerGAMGProcAgglomeration/eagerGAMGProcAgglomeration.H
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2013 OpenFOAM Foundation
+    Copyright (C) 2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -36,19 +37,16 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef eagerGAMGProcAgglomeration_H
-#define eagerGAMGProcAgglomeration_H
+#ifndef Foam_eagerGAMGProcAgglomeration_H
+#define Foam_eagerGAMGProcAgglomeration_H
 
 #include "GAMGProcAgglomeration.H"
-#include "DynamicList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
-class GAMGAgglomeration;
-
 /*---------------------------------------------------------------------------*\
               Class eagerGAMGProcAgglomeration Declaration
 \*---------------------------------------------------------------------------*/
@@ -57,30 +55,23 @@ class eagerGAMGProcAgglomeration
 :
     public GAMGProcAgglomeration
 {
-    // Private data
+    // Private Data
 
         //- Agglpmeration level
         const label mergeLevels_;
 
-        DynamicList<label> comms_;
-
-    // Private Member Functions
-
-        //- No copy construct
-        eagerGAMGProcAgglomeration
-        (
-            const eagerGAMGProcAgglomeration&
-        ) = delete;
-
-        //- No copy assignment
-        void operator=(const eagerGAMGProcAgglomeration&) = delete;
-
 
 public:
 
     //- Runtime type information
     TypeName("eager");
 
+    //- No copy construct
+    eagerGAMGProcAgglomeration(const eagerGAMGProcAgglomeration&) = delete;
+
+    //- No copy assignment
+    void operator=(const eagerGAMGProcAgglomeration&) = delete;
+
 
     // Constructors
 
@@ -98,9 +89,8 @@ public:
 
     // Member Functions
 
-       //- Modify agglomeration. Return true if modified
+        //- Modify agglomeration. Return true if modified
         virtual bool agglomerate();
-
 };
 
 
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/manualGAMGProcAgglomeration/manualGAMGProcAgglomeration.C b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/manualGAMGProcAgglomeration/manualGAMGProcAgglomeration.C
index a5d266015f..34bb3274fe 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/manualGAMGProcAgglomeration/manualGAMGProcAgglomeration.C
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/manualGAMGProcAgglomeration/manualGAMGProcAgglomeration.C
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2013-2015 OpenFOAM Foundation
+    Copyright (C) 2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -59,14 +60,8 @@ Foam::manualGAMGProcAgglomeration::manualGAMGProcAgglomeration
 
 // * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
-Foam::manualGAMGProcAgglomeration::
-~manualGAMGProcAgglomeration()
-{
-    forAllReverse(comms_, i)
-    {
-        UPstream::freeCommunicator(comms_[i]);
-    }
-}
+Foam::manualGAMGProcAgglomeration::~manualGAMGProcAgglomeration()
+{}
 
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
@@ -165,9 +160,8 @@ bool Foam::manualGAMGProcAgglomeration::agglomerate()
                     }
 
 
-                    // Allocate a communicator for the processor-agglomerated
-                    // matrix
-                    comms_.append
+                    // Communicator for the processor-agglomerated matrix
+                    comms_.push_back
                     (
                         UPstream::allocateCommunicator
                         (
@@ -178,7 +172,7 @@ bool Foam::manualGAMGProcAgglomeration::agglomerate()
 
                     // Use processor agglomeration maps to do the actual
                     // collecting
-                    if (Pstream::myProcNo(levelMesh.comm()) != -1)
+                    if (UPstream::myProcNo(levelMesh.comm()) != -1)
                     {
                         GAMGProcAgglomeration::agglomerate
                         (
@@ -186,7 +180,7 @@ bool Foam::manualGAMGProcAgglomeration::agglomerate()
                             procAgglomMap,
                             coarseToMaster,
                             agglomProcIDs,
-                            comms_.last()
+                            comms_.back()
                         );
                     }
                 }
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/manualGAMGProcAgglomeration/manualGAMGProcAgglomeration.H b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/manualGAMGProcAgglomeration/manualGAMGProcAgglomeration.H
index 71e0bad423..28485fd53a 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/manualGAMGProcAgglomeration/manualGAMGProcAgglomeration.H
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/manualGAMGProcAgglomeration/manualGAMGProcAgglomeration.H
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2013-2016 OpenFOAM Foundation
+    Copyright (C) 2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -58,11 +59,10 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef manualGAMGProcAgglomeration_H
-#define manualGAMGProcAgglomeration_H
+#ifndef Foam_manualGAMGProcAgglomeration_H
+#define Foam_manualGAMGProcAgglomeration_H
 
 #include "GAMGProcAgglomeration.H"
-#include "DynamicList.H"
 #include "Tuple2.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -70,8 +70,6 @@ SourceFiles
 namespace Foam
 {
 
-class GAMGAgglomeration;
-
 /*---------------------------------------------------------------------------*\
               Class manualGAMGProcAgglomeration Declaration
 \*---------------------------------------------------------------------------*/
@@ -80,26 +78,11 @@ class manualGAMGProcAgglomeration
 :
     public GAMGProcAgglomeration
 {
-    // Private data
+    // Private Data
 
         //- Per level the agglomeration map
         const List<Tuple2<label, List<labelList>>> procAgglomMaps_;
 
-        //- Any allocated communicators
-        DynamicList<label> comms_;
-
-
-    // Private Member Functions
-
-        //- No copy construct
-        manualGAMGProcAgglomeration
-        (
-            const manualGAMGProcAgglomeration&
-        ) = delete;
-
-        //- No copy assignment
-        void operator=(const manualGAMGProcAgglomeration&) = delete;
-
 
 public:
 
@@ -107,6 +90,13 @@ public:
     TypeName("manual");
 
 
+    //- No copy construct
+    manualGAMGProcAgglomeration(const manualGAMGProcAgglomeration&) = delete;
+
+    //- No copy assignment
+    void operator=(const manualGAMGProcAgglomeration&) = delete;
+
+
     // Constructors
 
         //- Construct given agglomerator and controls
@@ -123,9 +113,8 @@ public:
 
     // Member Functions
 
-       //- Modify agglomeration. Return true if modified
+        //- Modify agglomeration. Return true if modified
         virtual bool agglomerate();
-
 };
 
 
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/masterCoarsestGAMGProcAgglomeration/masterCoarsestGAMGProcAgglomeration.C b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/masterCoarsestGAMGProcAgglomeration/masterCoarsestGAMGProcAgglomeration.C
index 180ef2d385..721913d170 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/masterCoarsestGAMGProcAgglomeration/masterCoarsestGAMGProcAgglomeration.C
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/masterCoarsestGAMGProcAgglomeration/masterCoarsestGAMGProcAgglomeration.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2013-2014 OpenFOAM Foundation
-    Copyright (C) 2022 OpenCFD Ltd.
+    Copyright (C) 2022-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -101,12 +101,7 @@ Foam::masterCoarsestGAMGProcAgglomeration::masterCoarsestGAMGProcAgglomeration
 
 Foam::masterCoarsestGAMGProcAgglomeration::
 ~masterCoarsestGAMGProcAgglomeration()
-{
-    forAllReverse(comms_, i)
-    {
-        UPstream::freeCommunicator(comms_[i]);
-    }
-}
+{}
 
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
@@ -192,8 +187,8 @@ bool Foam::masterCoarsestGAMGProcAgglomeration::agglomerate()
                 }
 
 
-                // Allocate a communicator for the processor-agglomerated matrix
-                comms_.append
+                // Communicator for the processor-agglomerated matrix
+                comms_.push_back
                 (
                     UPstream::allocateCommunicator
                     (
@@ -203,7 +198,7 @@ bool Foam::masterCoarsestGAMGProcAgglomeration::agglomerate()
                 );
 
                 // Use processor agglomeration maps to do the actual collecting.
-                if (Pstream::myProcNo(levelComm) != -1)
+                if (UPstream::myProcNo(levelComm) != -1)
                 {
                     GAMGProcAgglomeration::agglomerate
                     (
@@ -211,7 +206,7 @@ bool Foam::masterCoarsestGAMGProcAgglomeration::agglomerate()
                         procAgglomMap,
                         masterProcs,
                         agglomProcIDs,
-                        comms_.last()
+                        comms_.back()
                     );
                 }
             }
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/masterCoarsestGAMGProcAgglomeration/masterCoarsestGAMGProcAgglomeration.H b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/masterCoarsestGAMGProcAgglomeration/masterCoarsestGAMGProcAgglomeration.H
index 8daaafa685..8d0a0de15a 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/masterCoarsestGAMGProcAgglomeration/masterCoarsestGAMGProcAgglomeration.H
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/masterCoarsestGAMGProcAgglomeration/masterCoarsestGAMGProcAgglomeration.H
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2013 OpenFOAM Foundation
-    Copyright (C) 2022 OpenCFD Ltd.
+    Copyright (C) 2022-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -57,19 +57,16 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef masterCoarsestGAMGProcAgglomeration_H
-#define masterCoarsestGAMGProcAgglomeration_H
+#ifndef Foam_masterCoarsestGAMGProcAgglomeration_H
+#define Foam_masterCoarsestGAMGProcAgglomeration_H
 
 #include "GAMGProcAgglomeration.H"
-#include "DynamicList.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
 {
 
-class GAMGAgglomeration;
-
 /*---------------------------------------------------------------------------*\
               Class masterCoarsestGAMGProcAgglomeration Declaration
 \*---------------------------------------------------------------------------*/
@@ -78,30 +75,25 @@ class masterCoarsestGAMGProcAgglomeration
 :
     public GAMGProcAgglomeration
 {
-    // Private data
+    // Private Data
 
         label nProcessorsPerMaster_;
 
-        DynamicList<label> comms_;
-
-
-    // Private Member Functions
-
-        //- No copy construct
-        masterCoarsestGAMGProcAgglomeration
-        (
-            const masterCoarsestGAMGProcAgglomeration&
-        ) = delete;
-
-        //- No copy assignment
-        void operator=(const masterCoarsestGAMGProcAgglomeration&) = delete;
-
 
 public:
 
     //- Runtime type information
     TypeName("masterCoarsest");
 
+    //- No copy construct
+    masterCoarsestGAMGProcAgglomeration
+    (
+        const masterCoarsestGAMGProcAgglomeration&
+    ) = delete;
+
+    //- No copy assignment
+    void operator=(const masterCoarsestGAMGProcAgglomeration&) = delete;
+
 
     // Constructors
 
@@ -119,9 +111,8 @@ public:
 
     // Member Functions
 
-       //- Modify agglomeration. Return true if modified
+        //- Modify agglomeration. Return true if modified
         virtual bool agglomerate();
-
 };
 
 
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C
index 3fe22a5e2f..d537dae584 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2013-2016 OpenFOAM Foundation
-    Copyright (C) 2019-2022 OpenCFD Ltd.
+    Copyright (C) 2019-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -231,12 +231,7 @@ Foam::procFacesGAMGProcAgglomeration::procFacesGAMGProcAgglomeration
 // * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
 Foam::procFacesGAMGProcAgglomeration::~procFacesGAMGProcAgglomeration()
-{
-    forAllReverse(comms_, i)
-    {
-        UPstream::freeCommunicator(comms_[i]);
-    }
-}
+{}
 
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
@@ -289,9 +284,8 @@ bool Foam::procFacesGAMGProcAgglomeration::agglomerate()
                         agglomProcIDs
                     );
 
-                    // Allocate a communicator for the processor-agglomerated
-                    // matrix
-                    comms_.append
+                    // Communicator for the processor-agglomerated matrix
+                    comms_.push_back
                     (
                         UPstream::allocateCommunicator
                         (
@@ -300,7 +294,6 @@ bool Foam::procFacesGAMGProcAgglomeration::agglomerate()
                         )
                     );
 
-
                     // Use processor agglomeration maps to do the actual
                     // collecting.
                     GAMGProcAgglomeration::agglomerate
@@ -309,7 +302,7 @@ bool Foam::procFacesGAMGProcAgglomeration::agglomerate()
                         procAgglomMap,
                         masterProcs,
                         agglomProcIDs,
-                        comms_.last()
+                        comms_.back()
                     );
                 }
             }
diff --git a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.H b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.H
index 7847a5c70d..eef59de0f0 100644
--- a/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.H
+++ b/src/OpenFOAM/matrices/lduMatrix/solvers/GAMG/GAMGProcAgglomerations/procFacesGAMGProcAgglomeration/procFacesGAMGProcAgglomeration.H
@@ -6,6 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2013 OpenFOAM Foundation
+    Copyright (C) 2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -39,11 +40,10 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef procFacesGAMGProcAgglomeration_H
-#define procFacesGAMGProcAgglomeration_H
+#ifndef Foam_procFacesGAMGProcAgglomeration_H
+#define Foam_procFacesGAMGProcAgglomeration_H
 
 #include "GAMGProcAgglomeration.H"
-#include "DynamicList.H"
 #include "labelField.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
@@ -51,11 +51,6 @@ SourceFiles
 namespace Foam
 {
 
-// Forward Declarations
-class GAMGAgglomeration;
-class lduMesh;
-class lduPrimitiveMesh;
-
 /*---------------------------------------------------------------------------*\
                     Class procFacesGAMGProcAgglomeration Declaration
 \*---------------------------------------------------------------------------*/
@@ -69,8 +64,6 @@ class procFacesGAMGProcAgglomeration
         //- When to processor agglomerate
         const label nAgglomeratingCells_;
 
-        //- Allocated communicators
-        DynamicList<label> comms_;
 
     // Private Member Functions
 
@@ -90,21 +83,19 @@ class procFacesGAMGProcAgglomeration
         //- Do we need to agglomerate across processors?
         bool doProcessorAgglomeration(const lduMesh&) const;
 
-        //- No copy construct
-        procFacesGAMGProcAgglomeration
-        (
-            const procFacesGAMGProcAgglomeration&
-        ) = delete;
-
-        //- No copy assignment
-        void operator=(const procFacesGAMGProcAgglomeration&) = delete;
-
 
 public:
 
     //- Runtime type information
     TypeName("procFaces");
 
+    //- No copy construct
+    procFacesGAMGProcAgglomeration(const procFacesGAMGProcAgglomeration&)
+        = delete;
+
+    //- No copy assignment
+    void operator=(const procFacesGAMGProcAgglomeration&) = delete;
+
 
     // Constructors