First, thank you for adopting little Saavik… as Anne said, try to see if your kids can give treats. Remember that at 2 years old, Saavik would be considered still young-at-heart, so a firm noise whenever she displays this behavior is important. (Pick something and have everyone in your family agree to the command- "Stop!", or "Uh-Uh"). I think positive reinforcement is important, especially from you (as she's roo'ed with you!).... Kindly remember that there may be some memory of a naughty child that Saavik is remembering, so make sure that your girls know to be gentle and to use a quiet, KIND voice... not to get too excited, if possible?
If Saavik nips again, you or your husband should promptly pick her up, say "Stop" or whatever you use, and carry her away from the group. Tell her, "No Bite" and as long as she's calm, put her down and walk away. When she comes back to you and your girls, tell her gently to "Be Nice"... "Good girl".... nice, calm praises.
I hope that everything works well for you! You sound like a great family for little Saavik to grow into. We adopted Lola when she was 1.5 years old, and we were her fourth "home".... she's been here 2 years now and she's a totally different (well adjusted) girl. Lola was very skittish at first, but as I type this, she is on my lap asleep.
Hugs and Roos- 
