At what point am I "locked in" to a park? If I have FP+ set up for AK on Thursday, when is the last time I can make change my park selection? Say on the morning of our AK day, we decide to go to DHS instead - can I drop my AK FP selections and book 3 for DHS (based on availability of course)? Or, if I make FP selections for AK in the afternoon, but we hit all the attractions in the AM then decide to park hop to MK, can I drop the FP and book the 3 for MK (we didn't use any in AK and the return times have still not passed)? Or is it after 12am the day before you are committed to a park? TIA!