Multiple credit cards on a service contract

Hi all-

We've got a requirement to accept multiple cards at the header level on a service contract. As we understand it, multiple cards can be applied to different lines or alternately, we could use multiple cards as a prepayment. And of course we could require a single card. None of these are optimal scenarios. Has anyone dealt with a situation where they accepted multiple cards on a service contract header? If so, any guidance would be massively appreciated.

Thanks in advance,

Joe