Harry and Meghan won't stay at BP, they would have to follow the rules set up by the King and the staff. I think after the time Serena posted the photo of herself in a private area of Windsor that was off limits to the public, the rules were really enforced for the couple.
I don't know if I believe this story, Charles goes along with the Crown Estates in removing the Harkles from Frogmore Cottage and now extends the "olive branch"? Again, it's the Royal Family that is "extending the olive branch"...I'll bet this came from the Sussexes.