diff --git a/src/dynamicMesh/fvMeshSubset/fvMeshSubset.H b/src/dynamicMesh/fvMeshSubset/fvMeshSubset.H
index fe193ab9a8..9ae47a8cde 100644
--- a/src/dynamicMesh/fvMeshSubset/fvMeshSubset.H
+++ b/src/dynamicMesh/fvMeshSubset/fvMeshSubset.H
@@ -73,7 +73,7 @@ namespace Foam
 
 class fvMeshSubset
 {
-    // Private data
+    // Private Data
 
         //- Mesh to subset from
         const fvMesh& baseMesh_;
@@ -214,13 +214,13 @@ public:
     // Access
 
         //- Original mesh
-        inline const fvMesh& baseMesh() const;
+        inline const fvMesh& baseMesh() const noexcept;
 
         //- Return baseMesh or subMesh, depending on the current state.
-        inline const fvMesh& mesh() const;
+        inline const fvMesh& mesh() const noexcept;
 
         //- Have subMesh?
-        inline bool hasSubMesh() const;
+        inline bool hasSubMesh() const noexcept;
 
         //- Return reference to subset mesh
         inline const fvMesh& subMesh() const;
@@ -491,7 +491,6 @@ public:
                 syncCouples
             );
         }
-
 };
 
 
diff --git a/src/dynamicMesh/fvMeshSubset/fvMeshSubsetI.H b/src/dynamicMesh/fvMeshSubset/fvMeshSubsetI.H
index 434935c050..b0f8bd9f86 100644
--- a/src/dynamicMesh/fvMeshSubset/fvMeshSubsetI.H
+++ b/src/dynamicMesh/fvMeshSubset/fvMeshSubsetI.H
@@ -27,19 +27,19 @@ License
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-inline const Foam::fvMesh& Foam::fvMeshSubset::baseMesh() const
+inline const Foam::fvMesh& Foam::fvMeshSubset::baseMesh() const noexcept
 {
     return baseMesh_;
 }
 
 
-inline const Foam::fvMesh& Foam::fvMeshSubset::mesh() const
+inline const Foam::fvMesh& Foam::fvMeshSubset::mesh() const noexcept
 {
     return fvMeshSubsetPtr_ ? *fvMeshSubsetPtr_ : baseMesh_;
 }
 
 
-inline bool Foam::fvMeshSubset::hasSubMesh() const
+inline bool Foam::fvMeshSubset::hasSubMesh() const noexcept
 {
     return bool(fvMeshSubsetPtr_);
 }
diff --git a/src/dynamicMesh/fvMeshSubsetProxy/fvMeshSubsetProxy.C b/src/dynamicMesh/fvMeshSubsetProxy/fvMeshSubsetProxy.C
index 133d31654f..e428291236 100644
--- a/src/dynamicMesh/fvMeshSubsetProxy/fvMeshSubsetProxy.C
+++ b/src/dynamicMesh/fvMeshSubsetProxy/fvMeshSubsetProxy.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2019 OpenCFD Ltd.
+    Copyright (C) 2016-2021 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -30,6 +30,18 @@ License
 #include "cellZone.H"
 #include "Time.H"
 
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+
+void Foam::fvMeshSubsetProxy::clearOut()
+{
+    subsetter_.clear();
+    type_ = subsetType::NONE;
+    name_.clear();
+    names_.clear();
+    selectedCells_.clearStorage();
+}
+
+
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 Foam::fvMeshSubsetProxy::fvMeshSubsetProxy(fvMesh& baseMesh)
@@ -37,16 +49,11 @@ Foam::fvMeshSubsetProxy::fvMeshSubsetProxy(fvMesh& baseMesh)
     baseMesh_(baseMesh),
     subsetter_(baseMesh),
     exposedPatchId_(-1),
-    type_(NONE),
+    type_(subsetType::NONE),
     name_(),
     names_(),
     selectedCells_()
-{
-    if (useSubMesh())
-    {
-        correct();
-    }
-}
+{}
 
 
 Foam::fvMeshSubsetProxy::fvMeshSubsetProxy
@@ -60,26 +67,23 @@ Foam::fvMeshSubsetProxy::fvMeshSubsetProxy
     baseMesh_(baseMesh),
     subsetter_(baseMesh),
     exposedPatchId_(exposedPatchId),
-    type_(selectionName.empty() ? NONE : type),
+    type_(selectionName.empty() ? subsetType::NONE : type),
     name_(),
     names_(),
     selectedCells_()
 {
-    if (type_ == ZONES)
+    if (type_ == subsetType::ZONES)
     {
         // Populate wordRes for ZONES
         names_.resize(1);
         names_.first() = selectionName;
     }
-    else if (type_ != NONE)
+    else if (type_ == subsetType::SET || type_ == subsetType::ZONE)
     {
         name_ = selectionName;
     }
 
-    if (useSubMesh())
-    {
-        correct();
-    }
+    correct();
 }
 
 
@@ -93,15 +97,12 @@ Foam::fvMeshSubsetProxy::fvMeshSubsetProxy
     baseMesh_(baseMesh),
     subsetter_(baseMesh),
     exposedPatchId_(exposedPatchId),
-    type_(ZONES),
+    type_(subsetType::ZONES),
     name_(),
     names_(zoneNames),
     selectedCells_()
 {
-    if (useSubMesh())
-    {
-        correct();
-    }
+    correct();
 }
 
 
@@ -115,23 +116,33 @@ Foam::fvMeshSubsetProxy::fvMeshSubsetProxy
     baseMesh_(baseMesh),
     subsetter_(baseMesh),
     exposedPatchId_(exposedPatchId),
-    type_(ZONES),
+    type_(subsetType::ZONES),
     name_(),
     names_(std::move(zoneNames)),
     selectedCells_()
 {
-    if (useSubMesh())
-    {
-        correct();
-    }
+    correct();
 }
 
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
+void Foam::fvMeshSubsetProxy::resetZones(const wordRes& zoneNames)
+{
+    fvMeshSubsetProxy::clearOut();
+
+    if (!zoneNames.empty())
+    {
+        type_ = subsetType::ZONES;
+        names_ = zoneNames;
+        correct();
+    }
+}
+
+
 bool Foam::fvMeshSubsetProxy::correct(bool verbose)
 {
-    if (type_ == NONE)
+    if (type_ == subsetType::NONE)
     {
         subsetter_.clear();
         selectedCells_.clearStorage();
@@ -142,7 +153,7 @@ bool Foam::fvMeshSubsetProxy::correct(bool verbose)
 
     bitSet selectedCells;
 
-    if (type_ == SET)
+    if (type_ == subsetType::SET)
     {
         if (verbose)
         {
@@ -157,7 +168,7 @@ bool Foam::fvMeshSubsetProxy::correct(bool verbose)
             selectedCells.set(idx);
         }
     }
-    else if (type_ == ZONE)
+    else if (type_ == subsetType::ZONE)
     {
         if (verbose)
         {
@@ -167,7 +178,7 @@ bool Foam::fvMeshSubsetProxy::correct(bool verbose)
         selectedCells.resize(nCells);
         selectedCells.set(baseMesh_.cellZones()[name_]);
     }
-    else if (type_ == ZONES)
+    else if (type_ == subsetType::ZONES)
     {
         if (verbose)
         {
diff --git a/src/dynamicMesh/fvMeshSubsetProxy/fvMeshSubsetProxy.H b/src/dynamicMesh/fvMeshSubsetProxy/fvMeshSubsetProxy.H
index f36ffcee9e..153177a385 100644
--- a/src/dynamicMesh/fvMeshSubsetProxy/fvMeshSubsetProxy.H
+++ b/src/dynamicMesh/fvMeshSubsetProxy/fvMeshSubsetProxy.H
@@ -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.
@@ -97,6 +97,9 @@ private:
 
     // Private Member Functions
 
+        //- Clear, set to NONE
+        void clearOut();
+
         //- No copy construct
         fvMeshSubsetProxy(const fvMeshSubsetProxy&) = delete;
 
@@ -142,21 +145,27 @@ public:
     // Access
 
         //- The entire base mesh
-        inline const fvMesh& baseMesh() const
+        const fvMesh& baseMesh() const noexcept
         {
             return baseMesh_;
         }
 
         //- The mesh subsetter
-        inline const fvMeshSubset& subsetter() const
+        const fvMeshSubset& subsetter() const noexcept
         {
             return subsetter_;
         }
 
-        //- Check if a sub-mesh is being used
-        inline bool useSubMesh() const
+        //- The mesh subsetter
+        fvMeshSubset& subsetter() noexcept
         {
-            return type_ != NONE;
+            return subsetter_;
+        }
+
+        //- True if sub-mesh should be used
+        bool useSubMesh() const noexcept
+        {
+            return type_ != subsetType::NONE;
         }
 
         //- Access either base-mesh or sub-mesh
@@ -171,13 +180,13 @@ public:
         }
 
         //- The associated (set or zone) name if any.
-        inline const word& name() const
+        const word& name() const noexcept
         {
             return name_;
         }
 
         //- The current cell selection, when subsetting is active
-        inline const bitSet& selectedCells() const
+        const bitSet& selectedCells() const noexcept
         {
             return selectedCells_;
         }
@@ -185,6 +194,9 @@ public:
 
     // Edit
 
+        //- Define the zones selection, subset the mesh accordingly
+        void resetZones(const wordRes& zoneNames);
+
         //- Update of mesh subset.
         //  Return true if the subset changed from previous call.
         bool correct(bool verbose = false);