I'd say give it time too. It took a good few months for our new kittens to be accepted by our existing tom and we've since introduced a puppy to the mix. They will adapt. But only the cats can decide what kind of relationship they will have when the dust settles. They may happily settle down for a cuddle from time to time and then have a good hiss afterwards just for good measure. My girl cats have always had too much to say for themselves As long as they're not going tooth for nail you're doing well.

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Mummy to 1 puppy, 3 cats, 3 chickens, 2 guinea pigs and 2 small children