How to get cats to accept each other

[MrsPnut]

We have cat that we have had for years, a much loved family pet who adored her life.
Unfortunately due to our dd1's relationship breakdown she had to move home and bring her 2 one year old cats with her, when they arrived neither had been speyed and they were in season.

So in the short term we shut the kittens upstairs and so our cat could still go out. Since then we have had both kittens speyed and they have been allowed out.

There have been problems with the more dominant of the kittens hissing and growling at her sister as well as attacking our original cat when she gets the chance so she is going to live with my MIL as an only cat.

My query is how do I get the remaining kitten and my cat to live harmoniously, we still have a lot of growling and hissing whenever they meet.

Have you done the bedding swapping and keeping them apart for a while thing? Our cats never accepted each other despite two being mum and kitten and being half brother to the male.

They just sort of ignored each other. With hatred.

We kept our new kitten upstairs with us for a while, swapped bedding/socks and introduced them to each other for short periods of time. Never had any trouble with hissing etc though their play fighting was a little difficult to get used to because it's so rough! They were siblings (not litter mates) though so not sure if that makes a difference.

I just leave them to it and they do get used to each other eventually. Cats can have a significant personal space, and as long as another cat doesn't invade it, they're usually okay.

Thanks, They don't really have bedding because they sleep wherever they please!

Dominant kitten went off to grandma this week and so I have just been leaving all the doors open and there have been a few scuffles and a lot of hissing and growling.

I keep telling them it's get along with each other or I'm making a pair of furry mittens out of them both