Dang... I typed up a big, long reply, and then my computer ate it...
Anyway, there *is* something called a "Share". It's been explained on the forums in the past. It uses multiple credit cards for room charging on a single reservation, but not every Front Desk CM knows how to do it (or that it's even possible). So if you're going to ask about it, make sure to use that phrase, that you'd like to "set up a Share".
But with that being said, we tried it back in September, and couldn't do it. The CM knew what we were talking about, seemed to know what he was doing, but the computer wasn't allowing him to do it. He eventually got his supervisor on the phone, and apparently it couldn't be done because of our vacation package.
Now, I didn't think to ask him if it was because of our *specific* package (Free Dining), or if it was because we had Dining, or if it was because we were on a Package and not a Room-Only reservation. (Questions I'll have to ask when we go back down in June)
So, you *might* have some luck if you're on a Room Only reservation... Just use the magic phrase "set up a Share", and give it a try.
As for other parts of the room-charging discussion...
As others have said, each room key has its own number. Those numbers are then printed next to each line-item on the bill, so you can easily figure out who bought what.
What'd I'd suggest doing is to stop by the Front Desk and get a printout of your bill. Bring it back to the room (or sit in the sun by the pool), figure out who owes what, and then go back to the Front Desk armed with the specifics. The CM will thank you! (We did exactly this back in September, and while the second CM grabbed a calculator and was prepared to add things up herself, she was quite relieved when we told her we'd already done all that, and that we could jsut tell her how much to charge to each card)
And make sure if you have other people paying portions of the bill, that you do it BEFORE midnight of your final night. In the wee overnight hours, they'll close out your bill and charge whatever balance there is to the credit card on file. While it can be fixed in the morning, it's a hassle you don't need.
Lastly, be aware that every time you use a credit card to pay a portion of your room bill, that card will replace the one that's currently on-file. So make sure that you either a) use the one you want to be on-file last, or b) have the CM switch the account back to the proper card when everyone else's transactions are done. Otherwise, on check-out day you might find your remaining balance being put onto the wrong person's credit card... (I hope that all made sense)
-Rob