How can a data picker value clear/reset when the parent filter condition is chnaged after the select

If there exists two data pickers on a form say A & B. B's data configuration query condition is to filter based on the 'A' selection.The query works if the selection is made in the sequence. That is,select A then select B, the query works as required.However, if you go back to A now, change the selection to some other value to fail the query condition for B and save the form, the query condition for B is no longer validated as it already holds value.