diff --git a/ApplicationLibCode/ProjectDataModel/RimGridCollection.cpp b/ApplicationLibCode/ProjectDataModel/RimGridCollection.cpp
index 598adac677..a3dd442710 100644
--- a/ApplicationLibCode/ProjectDataModel/RimGridCollection.cpp
+++ b/ApplicationLibCode/ProjectDataModel/RimGridCollection.cpp
@@ -22,10 +22,14 @@
 #include "RimEclipseView.h"
 #include "RimGridView.h"
 
+#include "RigLocalGrid.h"
 #include "RigMainGrid.h"
+#include "RigNestedHybridGridReconstructor.h"
 
 #include "cafPdmUiTreeOrdering.h"
 
+#include <set>
+
 //--------------------------------------------------------------------------------------------------
 ///
 //--------------------------------------------------------------------------------------------------
@@ -83,6 +87,33 @@ void RimGridInfo::setEclipseGridIndex( int index )
     m_eclipseGridIndex = index;
 }
 
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+void RimGridInfo::resetSimulatorGridIndices( int index )
+{
+    m_eclipseGridIndex = index;
+    m_additionalGridIndices.clear();
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+void RimGridInfo::addSimulatorGridIndex( int index )
+{
+    m_additionalGridIndices.push_back( index );
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+std::vector<int> RimGridInfo::simulatorGridIndices() const
+{
+    std::vector<int> indices = { m_eclipseGridIndex() };
+    indices.insert( indices.end(), m_additionalGridIndices.begin(), m_additionalGridIndices.end() );
+    return indices;
+}
+
 //--------------------------------------------------------------------------------------------------
 ///
 //--------------------------------------------------------------------------------------------------
@@ -318,7 +349,8 @@ std::vector<size_t> RimGridCollection::indicesToVisibleGrids() const
         {
             if ( gridInfo->isActive() )
             {
-                addIfValid( gridInfo->eclipseGridIndex() );
+                for ( int index : gridInfo->simulatorGridIndices() )
+                    addIfValid( index );
             }
         }
     }
@@ -375,6 +407,8 @@ void RimGridCollection::syncFromMainEclipseGrid()
         auto allTemporaryGrids  = m_temporaryLgrs->gridInfos();
         auto allPersistentGrids = m_persistentLgrs->gridInfos();
 
+        std::set<QString> groupedInfos;
+
         size_t gridCount = mainGrid->gridCount();
         for ( size_t i = 1; i < gridCount; i++ )
         {
@@ -399,18 +433,35 @@ void RimGridCollection::syncFromMainEclipseGrid()
             }
             else
             {
-                if ( m_persistentLgrs->containsGrid( gridName ) )
+                // Reconstructed nested hybrid LGRs are grouped into one entry per refinement level
+                const auto*   localGrid = dynamic_cast<const RigLocalGrid*>( grid );
+                const bool    isGrouped = localGrid && localGrid->isReconstructedGrid();
+                const QString infoName  = isGrouped ? RigNestedHybridGridReconstructor::levelGroupName( gridName ) : gridName;
+
+                RimGridInfo* existing = nullptr;
+                for ( auto* info : m_persistentLgrs->gridInfos() )
+                    if ( info->name() == infoName ) existing = info;
+
+                if ( existing )
                 {
-                    removeGridInfo( gridName, allPersistentGrids );
+                    removeGridInfo( infoName, allPersistentGrids );
+                    if ( isGrouped )
+                    {
+                        if ( groupedInfos.count( infoName ) )
+                            existing->addSimulatorGridIndex( (int)gridIndex );
+                        else
+                            existing->resetSimulatorGridIndices( (int)gridIndex );
+                    }
                 }
                 else
                 {
-                    auto gridInfo = new RimGridInfo();
-                    gridInfo->setName( gridName );
-                    gridInfo->setEclipseGridIndex( (int)gridIndex );
-                    gridInfo->setUiIconFromResourceString( ":/LGR16x16.png" );
-                    m_persistentLgrs->addGridInfo( gridInfo );
+                    existing = new RimGridInfo();
+                    existing->setName( infoName );
+                    existing->setEclipseGridIndex( (int)gridIndex );
+                    existing->setUiIconFromResourceString( ":/LGR16x16.png" );
+                    m_persistentLgrs->addGridInfo( existing );
                 }
+                if ( isGrouped ) groupedInfos.insert( infoName );
             }
         }
 
diff --git a/ApplicationLibCode/ProjectDataModel/RimGridCollection.h b/ApplicationLibCode/ProjectDataModel/RimGridCollection.h
index b1096ef1e0..a9b915d857 100644
--- a/ApplicationLibCode/ProjectDataModel/RimGridCollection.h
+++ b/ApplicationLibCode/ProjectDataModel/RimGridCollection.h
@@ -27,6 +27,8 @@
 
 #include <QString>
 
+#include <vector>
+
 class RigMainGrid;
 
 //==================================================================================================
@@ -47,6 +49,11 @@ public:
     QString name() const;
     int     eclipseGridIndex() const;
 
+    // A grid info can represent several grids (e.g. all reconstructed LGRs of one nested hybrid level)
+    void             resetSimulatorGridIndices( int index );
+    void             addSimulatorGridIndex( int index );
+    std::vector<int> simulatorGridIndices() const;
+
     caf::PdmFieldHandle* objectToggleField() override;
 
 protected:
@@ -58,6 +65,7 @@ private:
     caf::PdmField<bool>    m_isActive;
     caf::PdmField<QString> m_gridName;
     caf::PdmField<int>     m_eclipseGridIndex;
+    std::vector<int>       m_additionalGridIndices;
 };
 
 //==================================================================================================
diff --git a/ApplicationLibCode/ReservoirDataModel/RigNestedHybridGridReconstructor.cpp b/ApplicationLibCode/ReservoirDataModel/RigNestedHybridGridReconstructor.cpp
index 7fd4c00c90..b5efb86be7 100644
--- a/ApplicationLibCode/ReservoirDataModel/RigNestedHybridGridReconstructor.cpp
+++ b/ApplicationLibCode/ReservoirDataModel/RigNestedHybridGridReconstructor.cpp
@@ -35,6 +35,8 @@
 
 #include "RiaDefines.h"
 
+#include <QRegularExpression>
+
 #include <algorithm>
 #include <array>
 #include <climits>
@@ -267,6 +269,16 @@ bool RigNestedHybridGridReconstructor::reconstruct( RigEclipseCaseData* caseData
     return true;
 }
 
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+QString RigNestedHybridGridReconstructor::levelGroupName( const QString& gridName )
+{
+    static const QRegularExpression re( "^(LGR_NHG_L\\d+)(_\\d+)?$" );
+    const auto                      match = re.match( gridName );
+    return match.hasMatch() ? match.captured( 1 ) : gridName;
+}
+
 //--------------------------------------------------------------------------------------------------
 /// Build one RigLocalGrid by appending contiguous cells/nodes to the global arrays, copying the real
 /// geometry from the scattered flat refined cells, hiding the originals, and linking every LGR cell
diff --git a/ApplicationLibCode/ReservoirDataModel/RigNestedHybridGridReconstructor.h b/ApplicationLibCode/ReservoirDataModel/RigNestedHybridGridReconstructor.h
index dd85c6a9bb..9900d223bd 100644
--- a/ApplicationLibCode/ReservoirDataModel/RigNestedHybridGridReconstructor.h
+++ b/ApplicationLibCode/ReservoirDataModel/RigNestedHybridGridReconstructor.h
@@ -66,6 +66,9 @@ public:
     // Returns true if at least one refined region was reconstructed.
     static bool reconstruct( RigEclipseCaseData* caseData, const NestedHybridInput& input, QString* errorMessage = nullptr );
 
+    // "LGR_NHG_L4_2" -> "LGR_NHG_L4". Names not matching the nested hybrid pattern are returned unchanged.
+    static QString levelGroupName( const QString& gridName );
+
 private:
     // Build one RigLocalGrid of the given IJK dimensions. boxToFlat maps each local cell to its
     // source flat cell (UNDEFINED for holes); boxToParent maps each local cell to the parent (coarse)
diff --git a/ApplicationLibCode/UnitTests/RigNestedHybridGridReconstructor-Test.cpp b/ApplicationLibCode/UnitTests/RigNestedHybridGridReconstructor-Test.cpp
index 5cb5b1ac8e..6f96464f28 100644
--- a/ApplicationLibCode/UnitTests/RigNestedHybridGridReconstructor-Test.cpp
+++ b/ApplicationLibCode/UnitTests/RigNestedHybridGridReconstructor-Test.cpp
@@ -375,6 +375,16 @@ TEST_F( RigNestedHybridGridReconstructorTest, LgrNamesAreConsistent )
     EXPECT_GT( namesByLevel["LGR_NHG_L4"].size(), 1 );
 }
 
+//--------------------------------------------------------------------------------------------------
+/// Tree grouping: numbered component names collapse to their refinement level name.
+//--------------------------------------------------------------------------------------------------
+TEST( RigNestedHybridGridReconstructorNameTest, LevelGroupName )
+{
+    EXPECT_EQ( RigNestedHybridGridReconstructor::levelGroupName( "LGR_NHG_L4_12" ), QString( "LGR_NHG_L4" ) );
+    EXPECT_EQ( RigNestedHybridGridReconstructor::levelGroupName( "LGR_NHG_L2" ), QString( "LGR_NHG_L2" ) );
+    EXPECT_EQ( RigNestedHybridGridReconstructor::levelGroupName( "LGR1" ), QString( "LGR1" ) );
+}
+
 //--------------------------------------------------------------------------------------------------
 /// Results propagate to the reconstructed LGR cells: an active-cell-indexed STATIC result and the
 /// full-length REFINE input property (both loaded before reconstruction) must both carry, on an LGR