kitten breaks relationship

We had 2 grown male cats that were very close. (indoor/outdoor)  Then a few months ago, I got a new little kitten.  Both males hissed, and hated (avoided) the new kitten for a long time.  In fact, they wouldn't even come in the house to eat! (we had to start feeding them outdoors).Now, however, one of the grown males has taken a liking to the now 6 month old kitten and the other grown male hisses at both the other male(used to be his buddy), and the kitten! So, the kitten has broken up the relationship between my two grown male cats. Now, for the past month or so, my grown male (the one that has befriended the kitten), has been losing his fur like crazy.  Looks like he over grooms.  maybe nerves..although he isn't a nervous cat at all.  Could it be that he is upset about his buddy "shunning" him because he is now friends with the new cat?

[opus88]

hi...sounds like alot of complicated issues going on there!!.........is the new cat a female or male?...can be alot of jealousy and stress as well, usually that is resolved within a few weeks, cats are very territorial animals and even the scent of another cat in their home is enough to make them angry!!
as far as the over grooming, that can be a stress issue yes. Was the new kitty Vet checked for fleas?...just so he/she didn't bring any health concerns into your home??
If all 3 are males it will be very difficult for them all to be buddies, there will always have to be the 'alpha' male.
let us know how you are making out.