I did exactly the same as you. Don't worry they should be fine.
within 3 days mine were sleeping together and they are the best of friends.
That was fifteen years ago.
2 months ago we adopted Harley who's also a bsh and he's only one year old!
He also has fitted in very well with the other two.
When you bring your new kitten into the home just keep watch on them and maybe play a game with them that they both can join in.
I am sure you will have lots of fun.:
Let us know how you get on.

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