Hi, and welcome to PT. I have a multi cat household, and have never experienced issues with bringing in a new face. I began with a male, added a young female, and then had another male. The first two played tremendously, and then when the third came along, the girl and the new one played alot- kinda leaving the first one alone. This was ok, as he was older, and quite happy, I think.

Then, I added some more- and they seemed to bond very well. I have one male alpha cat, and a two year old female that tests the hierachy often- but she is quite happy to bond with me, and the alpha cat stays on top. Interestingly, the bonding shifts with new cats. The third cat to my herd bonds best with the the two year old female's brother!

All of my cats are spayed/nuetered, and I kept a pretty careful watch over the introduction period..

I have heard, but haven't experience it yet, that the newest you are thinking of introducing won't bond with you, but instead will choose one of the cats, and that might make you feel bad. It hasn't ever happened to me, they all bond really well to me.

Good luck, and of course, you always have room for one more!!