Hi, I Have A Foster Cat - Clean Bill Of

Hi, I have a foster cat - clean bill of health that I am introducing to my other two cats. He has attacked both by going up to them while they are sleeping and biting there fur off then running off. My older one has sustained most of the abuse. I have feliway, calming collars and recently calming food. Do you have any suggestions as to how I can prevent this behavior by the foster cat? he had been in a home with other cats prior to his owner passing away and being sent into the system. He is now gaining weight with me and I was hoping to keep him but now I'm not sure what to do.