I took in a little, pregnant stray a couple of years ago. She had her kittens in one of our outbuildings, but when they were weaned I brought her and the 2 little ones we've kept, into the house. I've got 2 other cats, who were 8yrs old at the time & they were, to say the least, a bit put out! I just let them find their own space and left the cat flap open. The stray didn't help matters, as she's a bit of a b..ch, but there's a sort of uneasy peace in the house now. I suppose it doesn't help in that all of the adult cats are tortoiseshell & they're known for their tempers! Oddly, though, although the mother cat intensely dislikes my older girls, one of them gets on fine with the female kitten and the other one adores the little male. As I say, there's a truce now and they just avoid each other. I'm sure yours will come round eventually, too, and so kind of you to take this poor wee cat in! Good luck, Kxx