I think it depends on a couple of things...theoretically, yes, I think it's possible to see all three shows in a single night (assuming there are 2 F! and 2 PtN being presented). However, the questions are, how important is a prime view, how time are you willing to invest in waiting for spot, and which show is more important (F! or PtN). My instinctive feel is that the least time option is probably to watch the first F!, the watch fireworks from the F! viewing area, and then find a spot for PtN. Assuming you either do the dining package or have a FP, you can probably get a good view of F! (in most cases - dining package for sure, FP is a little more hit-or-miss). The view for Fireworks is pretty good from the F! viewing area according to some reports, but by the time you get out of the F! viewing area, I'd guess that most (if not all) front row viewing spots along the parade route will be taken. Fighting traffic control is not going to be easy, so I would just go with whichever direction they send you, then start working your way up the parade route until you find a spot.
Otherwise, you're going to have to put in a fair amount of time waiting for the first PtN (assuming you want a front row or second row spot). I'd opt to watch the parade from somewhere very close to where you want to watch fireworks. Then as soon as the parade passes, move into your fireworks viewing area. After that, go with crowd control and make your way to F!. This option probably gives you a better view of PtN (maybe) and fireworks, but you're going to sacrifice time and (most likely) your F! view.