Yes, sure, but first, let's explore the place. As I said, I find it cool that some of the Vanguardians, as Sam, actually believe that there is the need of a Headquarter like the one they had before, oir even more advanced. If (I say IF) in the end a Headuqrter will not be built there, why not if Phil aquire it from Dawson to built his own villa/fortress?
Can Grissom and Bree move there too?
Sure, if they want. But from a credibility stand point, I think very rich people like Phil and Griss are not used to have roommates. While people like Mick, Danny, Larry was natural that found normal living in an apartment, I found always strange that Sam, Phil or Griss adapted to it. Super rich people usually like to live in their own palaces...