Most of the rides give you the "rider switch" pass at the entrance to the line. On most of these, they only asked us for FP's for the people riding first. So there are some tricky ways you can use it. Several times, we got FP's for 2 rides at the same time. Splash/BTMRR for example. We had 5 tickets (me, DW, DS10, DD7, DD4), so we'd get 2 FP's for Splash and 3 FP's for BTMRR. So DW and DS10 go on Splash with FP, then I take DS10 and DD7 on Splash with rider switch pass. Then DW, DS10, and DD7 go on BTMRR with FP, then I take DS10 and DD7 on BTMRR with rider switch pass.
You could do the same thing to ride the same ride multiple times since you only need to use FP's for the people who go first, not the people who do a baby swap after that.
Except RnRC! I need to have my RnRC. 
