Males accept females much better than other males.

When you introduce the new kitty, put her in a room by herself, to let them get used to each others scent for a day. Go in with her and sit on the floor, and show her she is accepted at your home now.

For Rocky, he will be curious, and may hiss up a storm, but if he keeps his ears UP and doesn't flatten them, it is all show. Flattened ears, precedes aggressive attacks.
He will probably do what I call "revenge eating"...eating her food, etc. I have found over the years that FOOD is the way to keep the peace. I now give each cat their own "treat" once a day. (that has eroded now a bit, and they ask more often, but I give in. Our oldest two are not fat so I give them a snack as well here and there). When cats see that the FOOD will be plentiful and no changes happen with it, they usually accept the newbie.

Our middle cat used to scream at cats who came by the windows. She belted one out at 6am one day, and scared us silly! But she has mellowed a bit. We don't have many cats who come by but lately we have 3. I think the tree that fell across the river, is providing a bridge for them. They are also attracted to our bird feeders.

When we got Oreo, I bought a new cat tree for her, thinking 3 cats=3 cat perches. That really helped her, as she sat up there feeling safe.(she didn't feel well after her shots as a kitten, and was homesick when we adopted her..kind of "depressed"). After two weeks, my husband said-- "well, you picked a Dud". But you know, she is really the best cat we've had. She follows him around like a dog. It is so cute watching them outside together!
She prances around him with her tail up and happy... It never ceases to move me. So with time she is most certainly NOT a dud. LOL

Here is a picture of Oreo with hubby... keeping him company while he reads on the dock --under his chair...the other cat is our old Queen Sheba.

I agree, that it would be difficult not to take them all!
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