PLEASE be sure to adopt from a shelter if at all possible.  Bring your
ferret with you to see how they interact.  If you have a girl, she may
not accept another girl if she had no cage mate for a year.  The females
seem particularly hostile towards other females *in my experiences.*  YOU
will be unhappy and burdened with two time outs.  The ferrets will be
unhappy.
 
Call the shelter, or course, ahead of time, and ask if it is alright to
bring your ferret in.  They may require proof of distemper shots, or
other things..  They know their ferrets and their personalities.  And
unlike a pet store, you can return the shelter ferret if you have tried
everything to the very best of your ability, but it is still not working.
 
PLEASE read up on all the things to do correctly to reintroduce the
ferrets at home, where your current ferret is da boss.
 
I think ferrets with no cage mates for a year think they are human.  It
can be VERY difficult to integrate....In my experiences...it was most
difficult dealing with the females...though I just adore the feistiness
of so many of those tiny ones.  I just admire the dickens out of them.
[Posted in FML issue 4858]