Hope some one can help...I am buying a 10-day PH, I really want to keep it flexible. The price difference between 8 day PH vs, 10 day PH is not that much, if I end up with unused days can I upgrade to a non-expiring tix for only those remaining days or will I have to pay the non-expiring price on the entire 10 day PH? I cannot justify paying the non-expiring cost on the entire 10 day PH bc there is always a chance we will use all 10 days this trip and then I wasted my money choosing that option. Anyone have experience upgrading to non-expiring with your unused days? TIA!!!