It can take a l-o-n-g time for cats to adjust to a new visitor. Especially older cats that have been used to having their domain to themselves.

My oldest cat Gracie still doesn't like Panda, my newest addition - and it's been a couple of years since we brought her in. They tolerate each other but there's no love lost between those two. My orange male kitty Tigger seems to get along with her better. They play and chase each other and occasionally have the dreaded hissing match - or stare each other down - but for the most part they get along.

If you can keep them separated for the most part and have supervised "visitation" times I think everyone will be happier. I know you hate to keep any of them cooped up in a bedroom but given the choice of having to give Cooper up to a shelter......I think he'd appreciate being in the bedroom much more. I'm so happy you're giving it a try. I wish I lived closer so I could help you.
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