If you do a search for threads with this type of topic you'll find loads of tips from people far more experienced than myself (i didn't want you to feel ignored).

From what i remember from reading them, keep them separate for a while & introduce them slowly. Scent swapping is good. I've had issues after one of mine has been for a stay at the vets & talc seems to work as well (they smell the same that way).

Good luck with the new kitten & show us the piccies when get her.

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Jo