The leading cause of feline behavior problems is other cats at home. Cat on cat aggression is not a pretty thing and neither is territorial spraying.  Cats are a non social species. Put cats together and you’ll see what experts call a domestic hierarchy develop.  It’s not exactly an alpha dog thing but  younger, submissive cats do need to find their place in the hierarchy.  Cats like to divide up the home territory.  So be sure to keep that in mind.  if your cats are all spayed and neutered, it will simplify things.  Try feline appeasement which comes in diffusers like a nightlight. It’s not a cure all but it could help in a multi-cat household.

Remember, your pets count!