OK.
leave rowsouce of the child combo blank.
in the interactivechange method of the parent combo do:
1) save the parent.id_pk to your form property you just created
2) childcombo.rowsource = Your childcombo SQL statement in quotes("")
3) childcombo.requery()
Work as if you don't need money
Love as if you've never been hurt before
Live as if this is your last day to live
Dance as if no one's watching
