Multiple PO numbers on job w/serial numbers

I have a customer who issue me releases of a part, they come in with different PO numbers and serial numbers. we run the releases under one job number. how can I get the purchase order numbers linked to the job number? if i build the job with several demand links it totals the number of serial numbers needed. how can I assign serial numbers for the different releases when the have different range numbers?
doesn't look like this is possible