Tell either Sasha or Bree you want to have sex when they're both in the same room (kitchen @ 2000 is a good time to catch them in the same room). The other will ask if they can join. Say yes. Minami's progression towards joining the home harem will begin after that assuming you have her love, submission and lesbian points where they need to be. 75, 50ish, 50ish should do it.