When we were planning our trip, we thought we would fly in late and have to fly out early, so we only bought 5 day tickets. Now our flights arrive early afternoon and depart 7 pm, so we are thinking of adding a day or two onto our tickets. Here is our problem: If we upgrade our tickets when we get there, after we use them on our first day, will all of our FP+ remain or will it delete our last day of FP+?