As above, it can be done at the front desk, but from my experience it isn't smooth sailing. Having stayed with my MIL on our reservation and having her on her own card, I checked the bill and it had all of her charges on my card despite the reservation stating it was on her own card. So I'm not sure the system is easy to navigate on this one. I always pop down to the front desk the day before we check out to go over all the bills and charges etc... That way you have a little time to correct any issues without missing transportation lol