Howdy, Nicky!
It sounds like you are ready for a nature-filled vacation in the Wild West at
The Campsites at Disney's Fort Wilderness Resort.
Nicky, while initially only the credit or debit card that was used during the
online check-in process will be registered to the account, you can visit the Pioneers at the
Reception Outpost (or as the City Folk call them, Cast Members at the Front Desk) and they will be happy to help register different credit cards to different Magic Bands for each family.
Nicky, have you considered
renting a golf cart for your trip into the wilderness? While I haven't been lucky enough to visit the old fort myself, I have heard that it helps some of my fellow townies get around. You can call (407) 824-2742 to see if any rentals are available for your dates.
Come on back here to planDisney if we can help round-up a few more answers for your upcoming vacation, Nicky.
Safe travels, partner!
Sarah B.