I went last week and I did not have FP books for those riding the second time only for those riding the first time. I had no issues even at 7DMT, SDD, and Flight of Passage. The way I do it is I book a FP for the headliner that my child can't ride and then I typically book another nearby attraction for that child and one adult. For instance at Soarin' I will book everyone a FP on Soarin and then myself and the too short child on Living with the Land, we will get the RS. Then everyone will ride Soarin while I take the little one on Living with the Land. Then I will ride Soarin while they get a snack at Sunshine Seasons. I do something similar for the other big attractions that have a height restrictions. I have not had a problem yet. No one has even asked about FPs when getting the RS.