I can understand your frustration. Managing work and the home front can be stressful by itself. In addition if children pose problems, it is indeed very difficult. I think that her behaviour at home is directly linked to her behaviour at school. As she cannot give it back at school, all her pent up frustration and anger is directed towards family members as this is a 'safe zone' for her. I think we need to address her inadequacies first. As a mother, do you think that if she is not ass good as her peers, is it because of her inabilities or is it because she has not got the right kind of exposure? If it is inabilities, I would suggest a detailed educational assessment by a psychologist which would explain her low grades also. If it is exposure, I think that with the limited time that you have, all concerned family members need to keep engaging her in conversation. Talk about everything from current affairs to household matters. Involve her in minor decisions. Help her to express her opinions. Discipline is crucial and you will have to do limit setting with her. There should be certain ground rules like picking up one's plate which all members have to follow. Let there be consequences for her actions, both positive and negative. Have a fixed schedule for her studies. Link all behaviours with consequences. However I would insist that first try to build a rapport with her so that she is comfortable in speaking to you. Be patient and be perseverant. You will see the change.