Mmmm... Tough call. The best thing to do is watch and see how they get along together when you're around. If they seem to be fine together, it should be pretty safe to leave them alone. When you think they're ready, try for short sessions of alone time at first. If you can figure out a way for them to be apart together, you may want to give that a shot. Before Mowg got the run of the place, he was caged, and I'd leave the door open to the room he was in so Zelda could go check him out whenever she felt like it. Of course, it helped a bit that Mowg adored Zelda from day one, even if she was all hissy at him.

When you have them together, I'd give Josie most of the attention to let her know she's still top cat. As Josie realizes that Brodie isn't there to take her place, she'll get along with him better. And who knows? Maybe she'll decide to take on the surrogate mommy role. Goodness knows I always thought it was the sweetest thing when I caught Zelda letting Mowg nurse off of her!