Thanks all for the good advice. I hadn't thought of having to get my ex to sign off on any add-on, even one for myself. Her name would be on the deed of the add-on as well as the master contract. Don't want that, so even more reason to pay off the loan early so I can take her name off.
but to make sure I've followed:
I could sell an add on separately from my master contract, go through ROFR on the open market, and transfer ownership. Or, I could gift an add-on to a family member, as long as I record it as a new deed, and Disney agrees to waive/pass the ROFR.
so it is possible for an add-on to become a separate contract, as long as I follow the respective procedures.
I will advise my friend to look for a re-sale, although I don't think there will be any available for AKL for a while.