So you’ve finally decided to introduce another kitty to your household. You don’t think there’s much to do as you already have one cat, except maybe add another food bowl and litter-box. Well, you are wrong. As the owner (I think) of five cats, I can tell you that each new kitty-addition must be “nursed” into the household fold gently and responsibly and with the knowledge that there will be kitty hell to pay behind the water bowl and litter-box!
Cats are very territorial and they do not like any kind of alteration in their daily schedules. When I introduced a kitten to my four other cats about five years ago, it looked like things would work right away because when I brought him home and let him out of the carrier, they all became very quiet. The new kitten, emboldened by their response, walked over to the king of the house, my male Persian Nero, and nudged him with his small head. Nero, who suddenly realized this new usurper was sipping water from HIS bowl, banged him on the head with his paw and hissed like a serpent. Undaunted, kitty went to play with his new world for a while. I could tell where he was because I could hear the steam arising all over the house with the hisses of all the other cats as he dared to approach.
Time does make thinks easier. Give the animals a chance to get acquainted. With a kitten, there is less of a threat of usurping territory, as it just wants any place at all in the hierarchy of the new world. Adopting an older cat works too, but can be a bit more problematic in that the animal may need more time to establish its own territory.
If things don’t work out, maybe you should consider changing YOUR territory. The neighbors up the street don’t have any cats. Maybe they have an extra bed and can put you up for a while until your cats figure everything out.
Good luck whatever you do and… Happy Cats!