so I will be making FPP on Sat night. our 1st day we won’t use park tickets but will use our xmas party tickets. when i make fpp - how does MDE know to use my xmas party ticket confirmation number versus my resort stay?

I think you will be able to book FP for party hours AND all the days of your ticket. I’ve read in other threads that this has worked for people. You might want to choose your 3 FP on ticket days first and then add ones for the party hours, just in case.