Hi.  I hope this isn't too late to help you.  I brought home
two new one-year old males to join my (at the time) two three
and four-year old females.  Peanut (the younger of the two)
really had a problem with the boys.  She would wait until they
got near them and lunge, making a very loud squeal.  I don't
think she ever actually bit them, but let me tell you, the boys
would scoot away from her as quickly as possible. Eventually
Peanut left them alone but any time she would wander near they
would scoot away.  She always got the best place to sleep, etc.
 Pretzel (my other female) was the only one who could sleep
with her.  And Peanut was a little tiny female, barely a pound.
 My boys were 3 and 3 1/2 pounds.  But I guess the size doesn't
matter.  As I say, eventually everyone got along fine and I
would see her sleeping with the boys now and then.
Unfortunately, Peanut had pancreatic tumors and had to be put
to sleep.  The six I have now seem to have absolutely NO
dominance issues at all.  Good luck on your project!
[Posted in FML issue 1026]