Cats can’t get along

We have 4 Cats Coca 4 years old smaller size Turkish angora

Socks 2 years old small Russian blue

Guppy 2 years old large Norwegian forest cat

Newest addition is John 6 years old - very large, obese, orange cat

We introduced them as normally as possible But the issue is he’s 17 lbs and when let roam free he wants to chase the smaller cat Socks, Socks is NOT a fan of this and hisses and runs away causing Coca to come into the picture and attack John.

Recently I’ve just kept my door shut and John has lived in my room when we’ve attempted to introduce them again but now we have an issue where Guppy has befriended John. But Coca will not allow John to leave the room and will attack / scare him back into my room and sit in my doorway and make sure he doesn’t leave. Not really sure what to do in the situation would love any advice