I am wondering how and if this can be done.  I would like to show a combobox as a column in the XamDataGrid. But when you click the button that would normally show the combobox dropdown part, instead I could get another XamDataGrid with the filtering enabled as well as the ability to add a new item that is bound to a different table.  Once the user selects a row, they can click an OK button and that would update the underlining combobox so that the value is now set to what was selected in the popup, just as a normal combobox would work.

How could I do this?  Since it would have the XamGrid and a button, do I need a usercontrol?  Or would I have to template the edit portion of the combobox column?  If so, how do I do that?