I am trying to have a combo in the grids with that functionality:
ControlSource is a logical field. Values in a combo are 'Yes' and 'No'. RowSource is a form's array. When I instantiate a form I am getting "Data mismatch ..." for the combo. Is there a way to design that kind of thing?

You cannot bind combo boxes to logical fields. The data type of the controlSOurce must be numeric or character data only.