I've just brought home two 9 week old baby ferrets to add to my 3. One Jill, one hob.  The hob is the sweetest thing, plays like my other ferrets. The jill....I've never encountered such a bad biter. She does not want to play, and when I try to engage her in play with a toy or my hand (big mistake, not doing that again) she starts coming at me with her tiny self and LATCHES! She bites so hard she draws blood nearly every time and will not let go and will hiss while she is latched. I had to use water to unlatch her. When she finally does let go, she immediately comes after me to latch on again! :( I tried scruffing/hissing and her bite just gets harder, deeper. The hob is the total opposite, he play bites but it's nothing but a tooth grazing your skin.

What can I do...I do not want her to become a full size jill ready to take my finger off.

can you tell us a little more about her?  Where are you, as in USA, UK?  Are your kits intact?  Any polecat in them?  

Welcome to the group!

THE DOOKS OF HAZARD

The babies are intact and will be neautered/spayed later on, I'm in the USA.  Not any polecat that I'm aware of. They are from two different litters. The female is cinnamon and the male is chocolate mitt

I guess you got a fireball.  You're gong to have to interact with her to get any kind of a bond.  you may need leather gloves.  The tan kind, not the blue/gray work gloves.  Have you tried time out for 5 minutes when she bites?  Can you just ignore her, or does she come at you?

THE DOOKS OF HAZARD

I would gate them off in one room.  I would also separated them for awhile.  Do some one on one with mom.
I have a ferret room in my home that I can gate off from rest of the house.  I would let one out in the gated
room and let him/her explorer that room for good hour or so.  Once, they get bored or settled into the room.
Then I would go into the room and sit on the floor.  I let the little one come up to me.  I usually have a big
stuff toy in my hand.  If I feel threaten (ferret is going to bit me)  then I just push the little one away with
the stuff toy.

Little one, needs to earn your trust.....it might take some time.  Be patience.