My kitten Sophie is a bit of a biter too. We've learned to avoid it: if you pick her up and she wants down, we put her down right away to avoid nips. If we pet her and she nips at us instead of loving on us, we know to just forget it. Most of the time, she's just like a baby, putting her mouth on things, not actually biting us. The only problem is when we take her to the vet - and she's not letting that vet come anywhere NEAR her!!! As for biting the other cat, the cats will resolve their issues on their own. Kittens just have to test their boundaries!! A sharp "NO!" and immediate removal of your hands (set her down if you're holding her, stop petting her if you were) can't hurt either. Good luck and just remember that she'll grow out of it!!