Thoughts on having an even number of cats?

I'm not sure I'd mess with a good setup. Cats are not naturally pack animals, although their ociation with humans has encouraged that behavior. But as you add new cats, you increase the potential for behavior issues like inappropriate urination and aggressiveness. I know my vet feels that problems begin to occur once you have over 3 cats, so if your 5 cat household is working, you're doing very well!