Determining how adjustments (credits) are applied to payments in Payables

Hello,  I've searched PeopleBooks and My Oracle Support and haven't found an answer to this.  We are in PeopleSoft 9.2 (through PUM 21).  We have several instances where there are multiple adjustment (credit) vouchers for a supplier and when a voucher for payment is selected, an adjustment will be applied.  But we can't figure out how the paycyle determines which adjustment voucher to apply to the payment.  In on case I can see five adjustment vouchers for one supplier (same remit to, location, addrseqnum, pay group, pay method, paycycle, payment handling, etc.) that have all been partially applied to a