<Grid xmlns:xcdg="http://schemas.xceed.com/wpf/xaml/datagrid">
<Grid.Resources>

 <xcdg:DataGridCollectionViewSource x:Key="cvs_employees"
                                    Source="{Binding Source={x:Static Application.Current},
                                                 Path=Employees}">

    <xcdg:DataGridCollectionViewSource.DetailDescriptions>
       <xcdg:DataRelationDetailDescription RelationName="Employee_Orders"
                                           Title="Employee Orders">
          <xcdg:DataRelationDetailDescription.DetailDescriptions>
             <xcdg:DataRelationDetailDescription RelationName="Order_OrderDetails"
                                                 Title="Order Details">
                <xcdg:DataRelationDetailDescription.ItemProperties>
                   <xcdg:DataGridItemProperty Name="UnitPrice" />
                   <xcdg:DataGridItemProperty Name="Quantity" />
                   <xcdg:DataGridItemProperty Name="Discount" />
                </xcdg:DataRelationDetailDescription.ItemProperties>
                <xcdg:DataRelationDetailDescription.StatFunctions>
                   <xcdg:SumFunction ResultPropertyName="sum_quantity"
                                     SourcePropertyName="Quantity" />
                   <xcdg:AverageFunction ResultPropertyName="average_unitprice"
                                         SourcePropertyName="UnitPrice" />
                </xcdg:DataRelationDetailDescription.StatFunctions>
             </xcdg:DataRelationDetailDescription>
          </xcdg:DataRelationDetailDescription.DetailDescriptions>
       </xcdg:DataRelationDetailDescription>
    </xcdg:DataGridCollectionViewSource.DetailDescriptions>
 </xcdg:DataGridCollectionViewSource>
</Grid.Resources>

<xcdg:DataGridControl x:Name="EmployeesGrid"
                    ItemsSource="{Binding Source={StaticResource cvs_employees}}"
                    ItemsSourceName="Employee Information"
                    AutoCreateDetailConfigurations="True">
 <xcdg:DataGridControl.DefaultDetailConfiguration>
    <xcdg:DefaultDetailConfiguration>
       <xcdg:DefaultDetailConfiguration.Footers>
          <DataTemplate>
             <xcdg:InsertionRow />
          </DataTemplate>
       </xcdg:DefaultDetailConfiguration.Footers>
    </xcdg:DefaultDetailConfiguration>
 </xcdg:DataGridControl.DefaultDetailConfiguration>
</xcdg:DataGridControl>
</Grid>