Hi. If there is enough time for this try the following. Log onto your pay pal account and see if you can use the transfer money tab and transfer funds from the debit cards that way into your pay pal account. You cannot specify that it is for that purchase, just that you are putting funds into your pay pal account.
If this works then once you have loaded the debit cards into your pay pal go back to invoice and click the pay now button.
I really do not know if this will work but it is worth a shot. basically it will be similar to just transferring from your checking account multiple times .
Good luck, jim
