Hello all, looking for some tips on introducing 1 cat to a group of 9.

So, info dump first. We’ve had a cat for several years that lives in our garage. She does not venture out anymore and we typically put her in a catio when we take the car out to go anywhere. We live near a back road that people speed on often and it just made me very nervous letting her go but the time has come where I feel she needs to be free again.

Now, back in November a stray showed up on our ring so I set out some food for her. After a couple of weeks I went out to see I could pet her and realized she was very, very pregnant. She’s since had that littler (3 lived) and ended up getting pregnant again before I could get her into the local shelter to be fixed. Her second litter is about 2 months old (5 lived) and they all live on our back porch roaming the back yard. Luckily we live on an acre so they have plenty of room to run around and be crazy.

I am going to try and introduce our garage cat to this group out doors (which will shrink as we’re not keeping any of the second litter) but obviously they are very territorial and trying to take our garage cat out to their domain did not go well. Lots of hissing and meowing and growling.

What are some things I can do to slowly get these cats to at the very least ignore each other? The ideal outcome would be for her to become friendly with these cats and join them in the backyard or wherever they want to go, but worst case would be that they run our garage cat off completely. As much as I love these new additions, our garage cat is my #1 without question and I would feel horrible if she ever felt she couldn’t come back to her home because of the backyard cats.

I have read about using towels and swapping them to get them more used to the different scents and slowly putting them in the same room together but are there any other tips or tricks any of you have used in a similar situation?

Thank you in advance!