how to access control in DataGrid.RowDetailsTemplate in runtime

how to access txtName in DataGrid.RowDetailsTemplate in runtime :
 
my code :
 

<DataGrid ColumnWidth="*" Name="dgUsers" Grid.ColumnSpan="5" Grid.Row="4" Margin="10,0,10,4"
                                  AutoGenerateColumns="False" CanUserAddRows="False" CanUserDeleteRows="False"
                                  IsReadOnly="True"
                                  SelectionMode="Single" SelectionUnit="FullRow" HeadersVisibility="Column">
                            <DataGrid.Columns>
                                <DataGridTextColumn x:Name="Name" Header="Name"  Binding="{Binding Path=Name}"/>
                                <DataGridTextColumn x:Name="Family" Header="Family"  Binding="{Binding Path=Family}"/>
                            </DataGrid.Columns>
                            <DataGrid.RowDetailsTemplate>
                                <DataTemplate>
                                    <Grid Margin="0,10,0,10" >
                                        <TextBox Name="txtName" Margin="0,2,0,2" Text="{Binding Path=Name}" />
                                        <TextBox Name="txtFamily" Margin="0,2,0,2" Text="{Binding Path=Family}" />
                                        <TextBox Name="txtUserName" Margin="0,2,0,2" Text="{Binding Path=UserName}"  />
                                            <Button Background="#FF7F9D0E" Height="60" Name="btnDelete" TabIndex="8" Width="60" Margin="30,0,30,0" Click="BtnDeleteClick">
                                    </Grid>
 
                                </DataTemplate>
                            </DataGrid.RowDetailsTemplate>
                        </DataGrid>

 

i want access to txtName in event BtnDeleteClick.