Magic band question for combined group

[bab736]

My parents are coming with us for their first trip to WDW and we are sharing a suite in BLT that we've paid for by renting points. My parents are just responsible for paying for their food and souvenirs. How does this work? I assume they can have their magic bands link to their own credit card if they don't want to bring their money into the parks, right? Is there a way for them to tell what credit card, if any, is linked to their bands? Do they get an invoice/bill like we do at the end of our stay? Is it emailed to them? Do they need to "close out" when we check out? Their names are in the room reservation along with ours if that makes a difference.

Or would it just be easier to have them pay with their credit card the whole time?