Hello,
Is everyone spayed and neutered? That might help settle down of the stress?
After that make sure everyone is healthy. At my clinic this would include an exam on all of the cats and perhaps even blood work.
Then we talk about a more gradual acclimation period. I’ve seen this be between two weeks to years. Cats are their own bosses. So they decide on their own terms
Good luck.
Hello,
I am not able to diagnose online. But I do think that it would be helpful to find a feline specialist. I would also talk about adding sq fluids to be done daily at home and an appetite stimulant while you try to figure out what is going on. In some cases I also recommend in clinic iv fluids to help diurese the kidneys.
I hope this helps.
Very best of luck.