Each introduction goes differently. It took 3 weeks with Thumper and Butterscotch. 2 weeks with Skinny. In the end you will know just how they are acting that being in the same room is ok. There is going to be lots of hissing, grawling, swatting (I love the swats in the air method LOL). They know each other exists. They can pick up your vibes, I would be near by but not in eye shot when they are exploring each other. If your tense they pick up on it, I found this out when we introduced Skinny to the gang. He was so small I thought Butterscotch and Thumper would sit on him. LOL I would have a water bottle handy but I would leave the room and let them explore. Everyone is getting along just fine.
Make sure you fuss over Ally, she is feeling like Conner is invading.

Gotta run, Skinny is playing to hard and jumping on Thumper of all places in the bath room. Gotta put my Ref outfit on. LOL

Good luck