The bank information in the F04572 work file is determined when the payment group is created, but it is the issuing company's funding bank account, not for the supplier. When the print program (R04572T2 or equivalent) is executed by the Write process, it looks up the supplier's bank information to be included in the F04572OW table. So you should be able to change the supplier bank information after the payment control group is created but before the Write process is executed.