Customer need the ability to apply multiple prepayment invoices to each sales order lines. For example, 1st prepayment is 30% down. 2nd prepayment is for an additional 30% at a predetermined point in time and a 3rd prepayment when order is ready to ship. Currently to do this a modification is required or the customer has to issue a prepayment credit to void the 1st prepayment and issue a new prepayment invoice for the increased amount and apply previous payments received.