Hi, I'm sorry but I don't have any real answers to your question. I really admire your intentions and wish you luck in integrating the cats. There is advice around on introducing cats to existing ones. I wanted to thank you really because we have just got 2 kittens and our older cat is finding it very hard to adjust and it wasn't until I read your thread and you mentioned that your cats had stayed away from the house, only coming back for food, that gave me some hope for the future!
One website that is useful is
Introducing your cat to other cats and dogs
There is other help there also. I think the one thing that I have found over the last week is to be positive! I did begin to wonder what on earth we had done to Gus when he didn't accept the new arrivals, but having read lots of other posts I am more confident that somehow we will reach an agreeable situation!