After listening to the TROS soundtrack a few time I started to hear something. I just found a video from back in August where someone else had noticed something before the soundtrack had come out or the very detailed plot leaks.
Basically it lays out that Kylo Ren’s theme (or motif if you prefer), Rey’s Theme, and Palpatine’s Theme are musically linked. Why in the world would Williams link Rey and Palpatine’s themes (he wrote Rey’s for The Force Awakens) unless there was something being planned at that point in time to link her to Palpatine. And Adam Driver said that nothing changed from the secretes Abrams told him during TFA to the end. I think this trilogy has been more planned out than we have thought. I’m not sure Palpatine was originally intended to come back, but I think Rey was intended to be related to him.