Michael,
 
    Stick with it.  They will eventually start getting along.  The biting
at the neck is a natural wrestling move among ferrets.  Clyde has to try
and establish his dominance.  One way to do this is to grab the new one by
the scruff and drag her around.  My Nibbles did this to our new one, Bits,
when we first brought her home.  Let Clyde do it, but break them up if it
gets too rough or the new one seems scared or starts screaming.  A lot of
times Bits would break free and attack Nibbles right back.  There was also
much chuckling going on so it seemed they were having fun.  Nibbles did
hiss after they would break apart, but I think it was more a "I'm the boss
and I'll do that again if you don't learn it" kind of hiss.  Other times
she would do it to try and keep Bits away from her when she was doing
something else.  As long as it doesn't come to bloodshed or injury, the new
one should be fine.  They are resilient little creatures these ferrets.
 
Jim, Kathy, Nibbles and Bits ("Hey, why do we sound like a dog food?")
[Posted in FML issue 1307]