The part detail table is where MRP looks to suggest jobs. You have to update that table where requirement = True and unfirm the order release in the part detail table as well. If you check unfirm release in Epicor the method handles this. if you are doing it through a BPM you need to add logic to unfirm the release in the partdtl table as well
I believe a Data Directive should do it. Its been about 4 years ago since I dealt with this so without looking into my directives archives I believe that should work