The website online checkin only allows you to register on credit card. Your daughters register their card when you get to port. Alternatively each quest has their own 'folio' number when they sign for things against your card so it is very easy to see who has charged each item (and get them to pay for it!).
IGNORE THAT - totally incorrect! Yes you CAN register a diff creditcard to each person if you want on the Online check in facility.
Yep! You sure can.