Former ferals + newcomers; possible recipe 4 disaster

Hissy sometime ago said that ferals behave differently towards other cats when they live in a house..
How true Hissy! I hadn't experienced that until I took in a another kitten to foster and adopt out.
Two of my cats are former ferals, they are both 1 year old..I knew my other cat Madam wouldn't like the foster but I thought Gerard will get along with the others, he's 6 mos, the ff's love to romp..dream on
Madam of course doesn't like him but just leaves him alone..both Clovis & Margaret are very angry at Gerard, specially Margaret.
I had him in a room for a week, she wouldn't leave the door and pace along the wall growling, more than ever she resembled a wildcat. Now I don't know if it's better with both out in the house, she doesn't attack him but is very cautious around him and growls when he's near..I can't say it's G's fault b/c I understand it's their nature, he being a kitten wants to play and is a bit pesky, I've given them lots of toys and hope he'll be adopted soon..really didn't plan to bring in another kitty but this Gerard is a stray dumped twice so..
here's his page in catster
http://www.catster.com/?142970
Anybody in Nebraska or Kansas would like him, he's a beauty!!

We recently borught in 3 ferals and my 20lb male, who normally adjusts quite quickly, hissed and screamed for days, even at me...and the ferals did the same back....it just took longer to adapt, but it has ben 2 months now and he cleans them and sleeps with them..I just think it takes longer, but very possible.

I think it boils down to the famous depends on the cat..I'm afraid that Margaret has a higher hunting instinct than other cats because her brother, also feral is more indifferent towards Gerard, it might get better, then again she might loose it and hurt him, he's so delicate and she's enormous compared to Gerard..anyways I try to distract them but Gerard is all kitten, a true pest