How can I help my step-child stop acting out in class?

I have a good relationship with the mother of my step kids but she doesnt have the best tact when it comes to discipline and has asked me to step in because our 7 year old is having behavior issues in class. Her dad is deployed and I know this is a large factor in the situation because she has not had this issue before. Her grades are excellent and I want to continue to reward her for that but we have to correct the behavior issue before it becomes a very serious problem. We have her seeing the guidance counciler on a weekly basis and I take her with me to the family readiness groups. She doesnt show other signs of depression or anythign along those lines but kids are very different then adults. I have talked with her about it several times but each day she has come home this week she has had to sign the behavior folder. I asked her to tell me what she needs from me to help and I have told her if it continues we will be donating 1 of her toys for every day there is an issue