u/pouritallonice

I've seen cat pheromone air freshener-type things online to make cats get along better. Do these things actually help?

We just got 2 kittens. My existing adult cat hates them and has a track record of being standoffish with other animals. The house is big enough that it's feasible to keep them permanently separated, but we don't want to do that. We've tried keeping them separate and switching blankets/toys but my adult cat just hisses at those blankets too. I'd really hate to return the kittens.