diff --git a/src/Avalonia.Controls/DefinitionBase.cs b/src/Avalonia.Controls/DefinitionBase.cs
index 2e0afc7fe7..0c696a1035 100644
--- a/src/Avalonia.Controls/DefinitionBase.cs
+++ b/src/Avalonia.Controls/DefinitionBase.cs
@@ -655,7 +655,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Collection of shared states objects for a single scope
         /// </summary>
-        private class SharedSizeScope
+        internal class SharedSizeScope
         {
             /// <summary>
             /// Returns SharedSizeState object for a given group.
@@ -690,7 +690,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Implementation of per shared group state object
         /// </summary>
-        private class SharedSizeState
+        internal class SharedSizeState
         {
             /// <summary>
             /// Default ctor.
@@ -900,9 +900,11 @@ namespace Avalonia.Controls
         /// Private shared size scope property holds a collection of shared state objects for the a given shared size scope.
         /// <see cref="OnIsSharedSizeScopePropertyChanged"/>
         /// </summary>
-        private static readonly AttachedProperty<SharedSizeScope> PrivateSharedSizeScopeProperty =
+        internal static readonly AttachedProperty<SharedSizeScope> PrivateSharedSizeScopeProperty =
             AvaloniaProperty.RegisterAttached<DefinitionBase, Control, SharedSizeScope>(
-                "PrivateSharedSizeScope");
+                "PrivateSharedSizeScope",
+                defaultValue: null,
+                inherits: true);
 
         /// <summary>
         /// Shared size group property marks column / row definition as belonging to a group "Foo" or "Bar".
diff --git a/src/Avalonia.Controls/Grid.cs b/src/Avalonia.Controls/Grid.cs
index eaa7cc11c3..269d7a3093 100644
--- a/src/Avalonia.Controls/Grid.cs
+++ b/src/Avalonia.Controls/Grid.cs
@@ -7,6 +7,7 @@ using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 using System.Threading;
 using Avalonia;
 using Avalonia.Collections;
@@ -922,8 +923,6 @@ namespace Avalonia.Controls
         /// </remarks>
         private void ValidateDefinitionsUStructure()
         {
-            
-
             if (ColumnDefinitionsDirty)
             {
                 ExtendedData extData = ExtData;
@@ -937,8 +936,6 @@ namespace Avalonia.Controls
                 }
                 else
                 {
-                    // extData.ColumnDefinitions.InternalTrimToSize();
-
                     if (extData.ColumnDefinitions.Count == 0)
                     {
                         //  if column definitions collection is empty
@@ -947,16 +944,26 @@ namespace Avalonia.Controls
                     }
                     else
                     {
+                        foreach(var definition in extData.DefinitionsU 
+                                               ?? Enumerable.Empty<DefinitionBase>())
+                            definition.OnExitParentTree();
+
                         extData.DefinitionsU = extData.ColumnDefinitions;
                     }
                 }
 
+                // adds index information.
+                for(int i = 0; i < extData.DefinitionsU.Count;i++)
+                {
+                    var definition = extData.DefinitionsU[i];
+                    definition.Index = i;
+                    definition.OnEnterParentTree();
+                }
+
                 ColumnDefinitionsDirty = false;
             }
 
             Debug.Assert(ExtData.DefinitionsU != null && ExtData.DefinitionsU.Count > 0);
-
-            
         }
 
         /// <summary>
@@ -969,8 +976,6 @@ namespace Avalonia.Controls
         /// </remarks>
         private void ValidateDefinitionsVStructure()
         {
-            
-
             if (RowDefinitionsDirty)
             {
                 ExtendedData extData = ExtData;
@@ -984,8 +989,6 @@ namespace Avalonia.Controls
                 }
                 else
                 {
-                    // extData.RowDefinitions.InternalTrimToSize();
-
                     if (extData.RowDefinitions.Count == 0)
                     {
                         //  if row definitions collection is empty
@@ -994,16 +997,26 @@ namespace Avalonia.Controls
                     }
                     else
                     {
+                        foreach(var definition in extData.DefinitionsV 
+                                               ?? Enumerable.Empty<DefinitionBase>())
+                            definition.OnExitParentTree();
+                        
                         extData.DefinitionsV = extData.RowDefinitions;
                     }
                 }
 
+                // adds index information.
+                for(int i = 0; i < extData.DefinitionsV.Count;i++)
+                {
+                    var definition = extData.DefinitionsV[i];
+                    definition.Index = i;
+                    definition.OnEnterParentTree();
+                }
+
                 RowDefinitionsDirty = false;
             }
 
             Debug.Assert(ExtData.DefinitionsV != null && ExtData.DefinitionsV.Count > 0);
-
-            
         }
 
         /// <summary>
diff --git a/tests/Avalonia.Controls.UnitTests/SharedSizeScopeTests.cs b/tests/Avalonia.Controls.UnitTests/SharedSizeScopeTests.cs
index 467c25bfc6..12d4df32e5 100644
--- a/tests/Avalonia.Controls.UnitTests/SharedSizeScopeTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/SharedSizeScopeTests.cs
@@ -12,6 +12,11 @@ namespace Avalonia.Controls.UnitTests
 {
     public class SharedSizeScopeTests
     {
+        public bool HasSharedSizeScope(Control control)
+        {
+            return control.GetValue(DefinitionBase.PrivateSharedSizeScopeProperty) != null;
+        }
+
         [Fact]
         public void All_Descendant_Grids_Are_Registered_When_Added_After_Setting_Scope()
         {
@@ -23,7 +28,7 @@ namespace Avalonia.Controls.UnitTests
             root.SetValue(Grid.IsSharedSizeScopeProperty, true);
             root.Child = scope;
 
-            Assert.All(grids, g => Assert.True(g.HasSharedSizeScope()));
+            Assert.All(grids, g => Assert.True(HasSharedSizeScope(g)));
         }
 
         [Fact]
@@ -37,7 +42,7 @@ namespace Avalonia.Controls.UnitTests
             root.Child = scope;
             root.SetValue(Grid.IsSharedSizeScopeProperty, true);
 
-            Assert.All(grids, g => Assert.True(g.HasSharedSizeScope()));
+            Assert.All(grids, g => Assert.True(HasSharedSizeScope(g)));
         }
 
         [Fact]
@@ -51,10 +56,10 @@ namespace Avalonia.Controls.UnitTests
             root.SetValue(Grid.IsSharedSizeScopeProperty, true);
             root.Child = scope;
 
-            Assert.All(grids, g => Assert.True(g.HasSharedSizeScope()));
+            Assert.All(grids, g => Assert.True(HasSharedSizeScope(g)));
             root.SetValue(Grid.IsSharedSizeScopeProperty, false);
-            Assert.All(grids, g => Assert.False(g.HasSharedSizeScope()));
-            Assert.Equal(null, root.GetValue(Grid.PrivateSharedSizeScopeProperty));
+            Assert.All(grids, g => Assert.False(HasSharedSizeScope(g)));
+            Assert.Equal(null, root.GetValue(DefinitionBase.PrivateSharedSizeScopeProperty));
         }
 
         [Fact]