How to introduce new cats to colony, need advice!

I've come upon a situation where I am adopting someones pet cats but the cats need to stay outdoors. I have plenty of shelter and plenty of food for them all, my biggest issue is how to have my stray/feral colony accept these cats so they wont be chased out of my yard continuously.

Right now the pet cats will follow me a few houses down to my house eagerly, which is great, but as soon as any of my strays see them, they are chased off and there is growling and screaming and hissing my strays start the fight. The pet cats try to ignore them and walk around them which is amazing but then when chased off they run away. Even the youngest strays who are only 2 and quite small never fought anybody are going after these cats its horrible for me to see. Every cat (stray and pet are fixed by the way)

I must have the pet cats stay in my yard (or at least be able to come in my yard to eat and sleep when they want) otherwise they will not have access to any food or shelter. There is no way I can keep them in my yard without them being able to run away and escape its impossible, and they go back to the house they used to live when they are chased away and I cant have them go back there because then they are too afraid to come back unless I walk down the block, and I cant keep doing this.

I have tried bringing items with my cats and the pets cats scent into each others yard to smell and they smell it, I think they have run into eachother before, its just that up until now they had there own places to eat far away from eachother and never had to stay near each other.

What can I do?

This is really important please reply!

Unless you have some kind of enclosure or someplace to keep them where they could be separated and feel safe until they are gotten used to by the colony, they will run away back to the area they feel safest because it has their scent on it.  You can make yourself and enclosure for cheaper than you can buy one.  There are plenty of ideas on the internet. 

I have not personally used this but a friend does. She has these large outdoor dog run (chain link) with a top as well. It is about 8 ft. by 12 ft. or maybe a bit smaller. We put a shelter inside the kennel's when relocating feral cats. This way the feral cats can acclimate to the new territory and the resident feral cats can come and investigate the newbies safely. It really works and if I ever have to relocate a number of feral cats, this is what I will use. When it comes time to release them from the kennels, just open the door and let them come and go freely. Most will run out anyway, but some like the safety of their kennel :lol3: Once they have moved out, then take down the kennel and leave the shelter in the exact same area for a bit. If the cat's upon release, go back to their old territory, there is not much you can do since it is so close from my understanding of what you describe. BUT the cats will know where to come for food/shelter etc. HOpefully, they will stick around once you release them. :nod: Best of luck