I tried that in February. I was traveling with a friend, whose name the room was reserved under. We tried setting up each of our magic bands with our own credit card (after being assured by the front-desk staff that this would work).
Well, it didn't work. I stopped by the front desk at AoA at the end of our second day, and found that all of the charges were going to my friend's credit card! Luckily, they could separate out whose charges were whose by our magic band number (which is listed for each transaction), so I had them separate mine out manually. I was assured again by the front desk CM that the charges would stay separate from that point forward.
Stopped by the front desk on Day Three, not trusting that it would be working right. The new charges were still going to my friend's card. Since AoA (a value resort) automatically charges the credit card when a $500 threshold is reached, this was scary!
I didn't want to have to go to the desk every day to get the charges separated out manually, so I gave up using my magic band for charging and just used a combination of cash and pulling out my credit card every time I had a charge for the rest of the week.
So my advice is not to trust them when they say they can keep the charges separate. Maybe they've fixed this problem since February, but I wouldn't count on it. And with three people in the room, it would be even more time-consuming to have the front desk separate the charges out manually every day.
Sorry!