We are going to universal for atleast one day. We haven't decided whether or not we will spend the second day at universal or go to a disney park. If we buy a one day ticket, is that ticket "upgradeable" to a two day ticket that same day? Or are we stuck having to buy a second one day ticket if we don't initially buy a two day. We figured we would let the kid decide whether or not they wanted to stay at universal or go to disney. One of them has never been there. I know you can do this with Disney tickets, but have no idea if that is even a possibility at universal.