annz,

I'm not Gibby, but I can offer you a link to the integration story of three young adult toms into my feline household back in 2005. Each cat presented different integration challenges, and all of the strategies I used during the process were described in the story. It's a long read, but I think you might find it both entertaining and educational.

Laurie

Here is a link that might be useful: The Integration of the Three Mouseketeers

Other than my first two cats who were kittens and litter mates, everyone else came into the household as an adult stray/shelter cat. So I had four good situations before my one bad one when the cat I adopted from a shelter was just too aggressive with one of my resident cats. It just wasn't going to work out so he went back to the shelter and I got the current "new" cat who gets along great.

I've always just brought the new one in and kept it in isolation for awhile both for health reasons and so they can get used to the idea of each other. I think I've usually kept the new cat confined for a couple weeks before I let them take a look at each other through the crack in the door. Depending on how that goes I might do that for a little while until I let them out together under supervision. Usually once the new cat has been out they don't want to go back into isolation but I don't leave them unattended together until they seem to be tolerating each other without a lot of hissing and growling.

Other than the one failed adoption the rest have grown to tolerate each other somewhere between two to four weeks. Some have become buddies, some have just peacefully coexisted. One of my first cats didn't become buddies with a newcomer for a few years until after his littermate died. The newest one became buddies with one cat after a week. The other cat just tolerates the newer one.

In one case I kept a new cat isolated for several months because he was very badly wounded, had to have a couple surgeries and had massive parasite infestation. By the time he finally got out everyone got along fine.

Hope this helps and hope everything works out with your situation.