My experience has been that the resorts will sell you whatever pass you want for whatever number of days you want at the time you check in. When you check in, try to get just one UPH pass for the ENTIRE trip - if the reservation agent balks, explain that you are switching hotels and show them your confirmation for the other hotel.... if necessary, ask for a manager and get some help. I would NOT buy two UPMs because it is, as someone else points out, more expensive that just buying one, because the cost per day decreases incrementally the more days you buy.