diff --git a/DataGridMultiselectManaging/IListItemConverter.vb b/DataGridMultiselectManaging/IListItemConverter.vb
new file mode 100644
index 0000000..6b19886
--- /dev/null
+++ b/DataGridMultiselectManaging/IListItemConverter.vb
@@ -0,0 +1,4 @@
+Public Interface IListItemConverter
+   Function Convert(ByVal masterListItem As Object) As Object
+   Function ConvertBack(ByVal targetListItem As Object) As Object
+End Interface
diff --git a/DataGridMultiselectManaging/MultiSelectorBehaviours.vb b/DataGridMultiselectManaging/MultiSelectorBehaviours.vb
new file mode 100644
index 0000000..1b43aee
--- /dev/null
+++ b/DataGridMultiselectManaging/MultiSelectorBehaviours.vb
@@ -0,0 +1,80 @@
+Imports System.Windows.Controls.Primitives
+Imports System.ComponentModel
+
+
+Public Class MultiSelectorBehaviours
+
+   Public Shared ReadOnly SynchronizedSelectedItemsProperty As DependencyProperty = DependencyProperty.RegisterAttached("SynchronizedSelectedItems", GetType(IList), GetType(MultiSelectorBehaviours), New PropertyMetadata(Nothing, AddressOf OnSynchronizedSelectedItemsChanged))
+   Public Shared ReadOnly SynchronizationManagerProperty As DependencyProperty = DependencyProperty.RegisterAttached("SynchronizationManager", GetType(SynchronizationManager), GetType(MultiSelectorBehaviours), New PropertyMetadata(Nothing))
+
+
+   Public Shared Function GetSynchronizedSelectedItems(ByVal dependencyObject As DependencyObject) As IList
+      Return CType(dependencyObject.GetValue(SynchronizedSelectedItemsProperty), IList)
+   End Function
+
+   Public Shared Sub SetSynchronizedSelectedItems(ByVal dependencyObject As DependencyObject, ByVal value As IList)
+      dependencyObject.SetValue(SynchronizedSelectedItemsProperty, value)
+   End Sub
+
+   Private Shared Function GetSynchronizationManager(ByVal dependencyObject As DependencyObject) As SynchronizationManager
+      Return CType(dependencyObject.GetValue(SynchronizationManagerProperty), SynchronizationManager)
+   End Function
+
+   Private Shared Sub SetSynchronizationManager(ByVal dependencyObject As DependencyObject, ByVal value As SynchronizationManager)
+      dependencyObject.SetValue(SynchronizationManagerProperty, value)
+   End Sub
+
+   Private Shared Sub OnSynchronizedSelectedItemsChanged(ByVal dependencyObject As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs)
+      If e.OldValue IsNot Nothing Then
+         Dim synchronizer As SynchronizationManager = GetSynchronizationManager(dependencyObject)
+         synchronizer.StopSynchronizing()
+         SetSynchronizationManager(dependencyObject, Nothing)
+      End If
+
+      Dim list As IList = TryCast(e.NewValue, IList)
+      Dim selector As Selector = TryCast(dependencyObject, Selector)
+
+      If list IsNot Nothing AndAlso selector IsNot Nothing Then
+         Dim synchronizer As SynchronizationManager = GetSynchronizationManager(dependencyObject)
+
+         If synchronizer Is Nothing Then
+            synchronizer = New SynchronizationManager(selector)
+            SetSynchronizationManager(dependencyObject, synchronizer)
+         End If
+
+         synchronizer.StartSynchronizingList()
+      End If
+   End Sub
+
+   Private Class SynchronizationManager
+      Private ReadOnly _multiSelector As Selector
+      Private _synchronizer As TwoListSynchronizer
+
+      Friend Sub New(ByVal selector As Selector)
+         _multiSelector = selector
+      End Sub
+
+      Public Sub StartSynchronizingList()
+         Dim list As IList = GetSynchronizedSelectedItems(_multiSelector)
+
+         If list IsNot Nothing Then
+            _synchronizer = New TwoListSynchronizer(GetSelectedItemsCollection(_multiSelector), list)
+            _synchronizer.StartSynchronizing()
+         End If
+      End Sub
+
+      Public Sub StopSynchronizing()
+         _synchronizer.StopSynchronizing()
+      End Sub
+
+      Public Shared Function GetSelectedItemsCollection(ByVal selector As Selector) As IList
+         If TypeOf selector Is MultiSelector Then
+            Return (TryCast(selector, MultiSelector)).SelectedItems
+         ElseIf TypeOf selector Is ListBox Then
+            Return (TryCast(selector, ListBox)).SelectedItems
+         Else
+            Throw New InvalidOperationException("Target object has no SelectedItems property to bind.")
+         End If
+      End Function
+   End Class
+End Class
diff --git a/DataGridMultiselectManaging/TwoListSynchronizer.vb b/DataGridMultiselectManaging/TwoListSynchronizer.vb
new file mode 100644
index 0000000..f443d53
--- /dev/null
+++ b/DataGridMultiselectManaging/TwoListSynchronizer.vb
@@ -0,0 +1,163 @@
+Imports System.Collections.Specialized
+
+Public Class TwoListSynchronizer
+   Implements IWeakEventListener
+
+   Private Shared ReadOnly DefaultConverter As IListItemConverter = New DoNothingListItemConverter()
+   Private ReadOnly _masterList As IList
+   Private ReadOnly _masterTargetConverter As IListItemConverter
+   Private ReadOnly _targetList As IList
+
+   Public Sub New(ByVal masterList As IList, ByVal targetList As IList, ByVal masterTargetConverter As IListItemConverter)
+      _masterList = masterList
+      _targetList = targetList
+      _masterTargetConverter = masterTargetConverter
+   End Sub
+
+   Public Sub New(ByVal masterList As IList, ByVal targetList As IList)
+      Me.New(masterList, targetList, DefaultConverter)
+   End Sub
+
+   Private Delegate Sub ChangeListAction(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
+
+   Public Sub StartSynchronizing()
+      ListenForChangeEvents(_masterList)
+      ListenForChangeEvents(_targetList)
+      SetListValuesFromSource(_masterList, _targetList, New Converter(Of Object, Object)(AddressOf ConvertFromMasterToTarget))
+
+      If Not TargetAndMasterCollectionsAreEqual() Then
+         SetListValuesFromSource(_targetList, _masterList, New Converter(Of Object, Object)(AddressOf ConvertFromTargetToMaster))
+      End If
+   End Sub
+
+   Public Sub StopSynchronizing()
+      StopListeningForChangeEvents(_masterList)
+      StopListeningForChangeEvents(_targetList)
+   End Sub
+
+   Public Function ReceiveWeakEvent(ByVal managerType As Type, ByVal sender As Object, ByVal e As EventArgs) As Boolean Implements IWeakEventListener.ReceiveWeakEvent
+      HandleCollectionChanged(TryCast(sender, IList), TryCast(e, NotifyCollectionChangedEventArgs))
+      Return True
+   End Function
+
+   Protected Sub ListenForChangeEvents(ByVal list As IList)
+      If TypeOf list Is INotifyCollectionChanged Then
+         CollectionChangedEventManager.AddListener(TryCast(list, INotifyCollectionChanged), Me)
+      End If
+   End Sub
+
+   Protected Sub StopListeningForChangeEvents(ByVal list As IList)
+      If TypeOf list Is INotifyCollectionChanged Then
+         CollectionChangedEventManager.RemoveListener(TryCast(list, INotifyCollectionChanged), Me)
+      End If
+   End Sub
+
+   Private Sub AddItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
+      Dim itemCount As Integer = e.NewItems.Count
+
+      For i As Integer = 0 To itemCount - 1
+         Dim insertionPoint As Integer = e.NewStartingIndex + i
+
+         If insertionPoint > list.Count Then
+            list.Add(converter(e.NewItems(i)))
+         Else
+            list.Insert(insertionPoint, converter(e.NewItems(i)))
+         End If
+      Next
+   End Sub
+
+   Private Function ConvertFromMasterToTarget(ByVal masterListItem As Object) As Object
+      Return If(_masterTargetConverter Is Nothing, masterListItem, _masterTargetConverter.Convert(masterListItem))
+   End Function
+
+   Private Function ConvertFromTargetToMaster(ByVal targetListItem As Object) As Object
+      Return If(_masterTargetConverter Is Nothing, targetListItem, _masterTargetConverter.ConvertBack(targetListItem))
+   End Function
+
+   Private Sub HandleCollectionChanged(ByVal sender As Object, ByVal e As NotifyCollectionChangedEventArgs)
+      Dim sourceList As IList = TryCast(sender, IList)
+
+      Select Case e.Action
+         Case NotifyCollectionChangedAction.Add
+            PerformActionOnAllLists(AddressOf AddItems, sourceList, e)
+         Case NotifyCollectionChangedAction.Move
+            PerformActionOnAllLists(AddressOf MoveItems, sourceList, e)
+         Case NotifyCollectionChangedAction.Remove
+            PerformActionOnAllLists(AddressOf RemoveItems, sourceList, e)
+         Case NotifyCollectionChangedAction.Replace
+            PerformActionOnAllLists(AddressOf ReplaceItems, sourceList, e)
+         Case NotifyCollectionChangedAction.Reset
+            UpdateListsFromSource(TryCast(sender, IList))
+         Case Else
+      End Select
+   End Sub
+
+   Private Sub MoveItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
+      RemoveItems(list, e, converter)
+      AddItems(list, e, converter)
+   End Sub
+
+   Private Sub PerformActionOnAllLists(ByVal action As ChangeListAction, ByVal sourceList As IList, ByVal collectionChangedArgs As NotifyCollectionChangedEventArgs)
+      If sourceList Is _masterList Then
+         PerformActionOnList(_targetList, action, collectionChangedArgs, New Converter(Of Object, Object)(AddressOf ConvertFromMasterToTarget))
+      Else
+         PerformActionOnList(_masterList, action, collectionChangedArgs, New Converter(Of Object, Object)(AddressOf ConvertFromTargetToMaster))
+      End If
+   End Sub
+
+   Private Sub PerformActionOnList(ByVal list As IList, ByVal action As ChangeListAction, ByVal collectionChangedArgs As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
+      StopListeningForChangeEvents(list)
+      action(list, collectionChangedArgs, converter)
+      ListenForChangeEvents(list)
+   End Sub
+
+   Private Sub RemoveItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
+      If e.OldItems.Count = 1 AndAlso e.OldStartingIndex <= list.Count - 1 Then
+         list.RemoveAt(e.OldStartingIndex)
+      Else
+         For Each Item In e.OldItems
+            list.Remove(Item)
+         Next
+      End If
+   End Sub
+
+   Private Sub ReplaceItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
+      RemoveItems(list, e, converter)
+      AddItems(list, e, converter)
+   End Sub
+
+   Private Sub SetListValuesFromSource(ByVal sourceList As IList, ByVal targetList As IList, ByVal converter As Converter(Of Object, Object))
+      StopListeningForChangeEvents(targetList)
+      targetList.Clear()
+
+      For Each o As Object In sourceList
+         targetList.Add(converter(o))
+      Next
+
+      ListenForChangeEvents(targetList)
+   End Sub
+
+   Private Function TargetAndMasterCollectionsAreEqual() As Boolean
+      Return _masterList.Cast(Of Object)().SequenceEqual(_targetList.Cast(Of Object)().[Select](Function(item) ConvertFromTargetToMaster(item)))
+   End Function
+
+   Private Sub UpdateListsFromSource(ByVal sourceList As IList)
+      If sourceList Is _masterList Then
+         SetListValuesFromSource(_masterList, _targetList, New Converter(Of Object, Object)(AddressOf ConvertFromMasterToTarget))
+      Else
+         SetListValuesFromSource(_targetList, _masterList, New Converter(Of Object, Object)(AddressOf ConvertFromTargetToMaster))
+      End If
+   End Sub
+
+   Friend Class DoNothingListItemConverter
+      Implements IListItemConverter
+
+      Public Function Convert(ByVal masterListItem As Object) As Object Implements IListItemConverter.Convert
+         Return masterListItem
+      End Function
+
+      Public Function ConvertBack(ByVal targetListItem As Object) As Object Implements IListItemConverter.ConvertBack
+         Return targetListItem
+      End Function
+   End Class
+End Class
diff --git a/Special-Doors/MTableDbV.xaml b/Special-Doors/MTableDbV.xaml
index ae8099c..afd788f 100644
--- a/Special-Doors/MTableDbV.xaml
+++ b/Special-Doors/MTableDbV.xaml
@@ -142,21 +142,24 @@
                      <Grid>
                         <FrameworkElement x:Name="dummyElement" Visibility="Collapsed"/>
                         <DataGrid Name="AssociationDataGrid"
-                           ItemsSource="{Binding Path=SelectedItem.AssociationList,
+                                  ItemsSource="{Binding Path=SelectedItem.AssociationList,
                                                         ElementName=TablesListBox}"
-                           SelectedItem="{Binding Path=SelectedItem.SelectedAssociation,
-                                                         ElementName=TablesListBox,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
-                           IsSynchronizedWithCurrentItem="False"
-                           AutoGenerateColumns="False"
-                           CanUserSortColumns="False"
-                           CanUserResizeColumns="False"
-                           CanUserResizeRows="False"
-                           CanUserReorderColumns="False"
-                           SelectionMode="Single"
-                           ScrollViewer.CanContentScroll="True" 
-                           ScrollViewer.VerticalScrollBarVisibility="Auto"
-                           ScrollViewer.HorizontalScrollBarVisibility="Hidden"
-                           VirtualizingStackPanel.IsVirtualizing="False">
+                                  EgtCAM5:MultiSelectorBehaviours.SynchronizedSelectedItems="{Binding SelectedItem.SelectedAssociations,
+                                                         ElementName=TablesListBox}"
+                                  IsSynchronizedWithCurrentItem="False"
+                                  AutoGenerateColumns="False"
+                                  CanUserSortColumns="False"
+                                  CanUserResizeColumns="False"
+                                  CanUserResizeRows="False"
+                                  CanUserReorderColumns="False"
+                                  SelectionMode="Extended"
+                                  PreviewMouseDown="DataGrid_PreviewMouseDown"
+                                  PreviewMouseUp="DataGrid_PreviewMouseUp"
+                                  PreviewMouseMove="DataGrid_PreviewMouseMove"
+                                  ScrollViewer.CanContentScroll="True" 
+                                  ScrollViewer.VerticalScrollBarVisibility="Auto"
+                                  ScrollViewer.HorizontalScrollBarVisibility="Hidden"
+                                  VirtualizingStackPanel.IsVirtualizing="False">
                            <Interactivity:Interaction.Behaviors>
                               <EgtCAM5:ScrollIntoViewForDataGrid/>
                            </Interactivity:Interaction.Behaviors>
@@ -389,6 +392,7 @@
                               <DataGridTextColumn Header="Link"
                                                   Binding="{Binding Path=Link}"
                                                   Foreground="Black"
+                                                  IsReadOnly="True"
                                                   Visibility="{Binding Path=DataContext.Link_Visibility, Source={x:Reference dummyElement}}"/>
                            </DataGrid.Columns>
                         
@@ -555,6 +559,18 @@
                <ColumnDefinition Width="2*"/>
                <ColumnDefinition Width="1*"/>
                <ColumnDefinition Width="1*"/>
+               <ColumnDefinition >
+                  <ColumnDefinition.Style>
+                     <Style TargetType="{x:Type ColumnDefinition}">
+                        <Setter Property="Width" Value="1*"/>
+                        <Style.Triggers>
+                           <DataTrigger Binding="{Binding Visibility, ElementName=LinkBtn}" Value="Collapsed">
+                              <Setter Property="Width" Value="Auto"/>
+                           </DataTrigger>
+                        </Style.Triggers>
+                     </Style>
+                  </ColumnDefinition.Style>
+               </ColumnDefinition>
                <ColumnDefinition Width="1*"/>
                <ColumnDefinition Width="1*"/>
                <ColumnDefinition Width="2*"/>
@@ -601,24 +617,25 @@
                     CommandParameter="{Binding Path=SelectedItem, ElementName=TablesListBox}"
                     IsEnabled="{Binding MoveRow_IsEnabled}"
                     Grid.Column="4"/>
+            <Button x:Name="LinkBtn" Content="Link" Command="{Binding LinkCommand}"
+                    CommandParameter="{Binding Path=SelectedItem, ElementName=TablesListBox}"
+                    IsEnabled="{Binding Link_IsEnabled}"
+                    Visibility="{Binding Link_Visibility}"
+                    Grid.Column="5"/>
             <Button Content="Group" Command="{Binding GroupCommand}"
                     CommandParameter="{Binding Path=SelectedItem, ElementName=TablesListBox}"
                     IsEnabled="{Binding Group_IsEnabled}"
-                    Grid.Column="5"/>
-            <!--<Button Content="Link" Command="{Binding LinkCommand}"
-                    CommandParameter="{Binding Path=SelectedItem, ElementName=TablesListBox}"
-                    IsEnabled="{Binding Group_IsEnabled}"
-                    Grid.Column="5"/>-->
+                    Grid.Column="6"/>
             <Button Content="Position" Command="{Binding PositionCommand}"
                     CommandParameter="{Binding Path=SelectedItem, ElementName=TablesListBox}"
                     IsEnabled="{Binding Position_IsEnabled}"
-                    Grid.Column="6"/>
+                    Grid.Column="7"/>
             <Button Content="{Binding AddMachBtn}" Command="{Binding AddMachCommand}"
-               CommandParameter="{Binding Path=SelectedItem, ElementName=TablesListBox}"
-               Grid.Column="7"/>
+                    CommandParameter="{Binding Path=SelectedItem, ElementName=TablesListBox}"
+                    Grid.Column="8"/>
             <Button Content="{Binding RemoveMachBtn}" Command="{Binding RemoveMachCommand}"
-               CommandParameter="{Binding Path=SelectedItem, ElementName=TablesListBox}"
-               Grid.Column="8"/>
+                    CommandParameter="{Binding Path=SelectedItem, ElementName=TablesListBox}"
+                    Grid.Column="9"/>
          </Grid>
 
       </Grid>