Триггер флажок Combobox wpf

<ComboBox Name="identifiercombo" Text="{Binding SelectedIdentifier, UpdateSourceTrigger=PropertyChanged}"  ItemsSource="{Binding IdentifierCollection}"  SelectedIndex="0" IsEditable="True" Grid.Row="3" Grid.Column="1" HorizontalAlignment="Stretch" Margin="10,5">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal">
                <CheckBox Click="CheckBox_Click" Content="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Content,UpdateSourceTrigger=PropertyChanged}" VerticalAlignment="Center"/>                            
            </StackPanel>
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>
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