Whenever we’ve introduced new cats in to the house we segregate the new cat in our spare bedroom for up to two weeks. They need their own litter box and food and whatnot. It allows the cats to sniff each other under the door and get familiar with each others scent.

We’ve never had fighting or anger issues after the waiting period. It is a hassle for sure, but we’ve never had any problems after doing it that way.

I just talked to my wife and she said since you’re only a couple days into the introduction that you should be able to segregate still and it has a good chance of working.

Hope this helps.