We are headed to USO after Christmas and currently have 3-day park-to-park tickets. Our flight into Orlando arrives earlier than planned, so we are considering adding a 4th day to enjoy the park as soon as we arrive. I know I can easily add a day to my tickets, but my question is about timing. When I called to upgrade my tickets, it cost over $450 to add a 4th day for the five of us (my tickets were bought 18 months ago at a great discount), which I can't quite justify. However, I saw some posts from several years ago saying that if we use the tickets first, we will get credited "full gate value" and would then be able to add a 4th day for $10-20 a person (vs. $90 now). Can anyone confirm this? Thank you in advance.