title: Bind to the CollectionViewSource of a parent control
body: <p>I have a composite view that is made up by a parent user control (Counterparties_MainWindow) with to embeded user controls (Counterparties_UserInputs and Counterparties_SystemDetails):</p>
  
  <pre><code>&lt;UserControl x:Class="Counterparties_MainWindow"&gt;
  &lt;av:UserControl.Resources&gt;
      &lt;ResourceDictionary&gt;
          &lt;ResourceDictionary.MergedDictionaries&gt;
              &lt;ResourceDictionary Source="Counterparties_Dictionary.xaml" /&gt;
          &lt;/ResourceDictionary.MergedDictionaries&gt;
          &lt;CollectionViewSource x:Key="counterpartiesDataView" Source="{Binding Path=CounterpartiesData}" /&gt;
      &lt;/ResourceDictionary&gt;
  &lt;/av:UserControl.Resources&gt;
  
  &lt;DockPanel&gt;
     &lt;DockPanel&gt;
         &lt;GUI:Counterparties_UserInputs x:Name="UserInputs"/&gt;
         &lt;GUI:Counterparties_SystemDetails x:Name="SystDetails"/&gt;
     &lt;/DockPanel&gt;
  &lt;/DockPanel&gt;
  </code></pre>
  
  <p>The "Counterparties_SystemDetails" contains a grid that displays some already defined fields from the CounterpartiesData (a list of objects).
  The "Counterparties_UserInputs" displays the list of not yet defined fields from the CounterpartiesData that should be defined by the user.</p>
  
  <p>I used to have the CollectionViewSource in the Counterparties_SystemDetails user control xaml and was binding directly the grid to it, it was working (i.e. displaying me the CounterpartiesData details):</p>
  
  <pre><code>&lt;DataGrid Name="CounterpartiesGrid" ItemsSource="{Binding Source={StaticResource counterpartiesDataView}}"
  SelectedItem="{Binding Path=SelectedCounterparty, Mode=OneWayToSource}"  Style="{StaticResource DataGridStyle}"&gt;
  </code></pre>
  
  <p>However, now that I've moved the CollectionViewSource to the parent window in order to share the same CounterpartiesData object in both sub controls, I can't find any way to bind it back to my grid. Would you please kindly have some tips on how to do so?</p>
  
  <p>Last but not least, I would like to display the current selected counterpaty name in a text box field of the user control Counterparties_UserInputs. Would you know how I could access it easily?</p>
  
  <p>Thank you!</p>