Hi there! I manage a bunch of local pages under our corporate profile umbrella and did this not too long ago! This article has step-by-step instructions on how I did: Merge 2 Facebook Pages | Facebook Help Center. I found that the pages must be in New Pages Experience, and I could only do a few pages at once, then it stopped letting me for some reason? lol not sure why, but I’m still working through merging some of them. Hopefully this helps!