New Post: mark all the options in checkcombobox checked for the initial load.

I am using checkcombox for the header item of datagrid. The values in the checkcombox is coming from one of the view model property.

<DataTemplate x:Key="FilterHeaderTemplate" DataType="vm:HeaderContextItemViewModel">
 <StackPanel Orientation="Vertical" Tag="{Binding Path=Name}">
<Label Content="{Binding Path=Name}" Foreground="Black"></Label>
 <xctk:CheckComboBox x:Name="cbcheckbox" ItemsSource="{Binding Path=Values,IsAsync=False}" Tag="{Binding Path=Id}"
                                    ItemSelectionChanged="CheckComboBox_ItemSelectionChanged" Width="100">
                </xctk:CheckComboBox>

when it loads for the first time, i want all the options in that checkcombobox as checked ? is that possible to do that ?
Also, i can not do that from code behind as the values are coming from binding the property.