How do you introduce a kitten to your cat without a spare room?

Adults cats usually will not hurt a kitten, unless they are deranged or crazy or something. They may not welcome the kitten, at least at first, but usually they can sense that it's a just a baby, and they won't hurt it.

I have had cats all my life, so I've had a lot of experience bringing a new kitten into a home with adult cats. Sometimes the cat doesn't like the kitten, and hisses at it or swats at it, but after awhile they will get used to the kitten.

It's okay if you don't have a spare room. You don't have to keep them apart. But don't force them to interact; let them develop a relationship on their own time.