Dr. Jenny Isaacs explains, in this vlog entry, how the family unit is an important piece when treating children.
There is a great deal of research based evidence to support this practice, some of which can be found using these links:
Hemphill, S.A. & Littlefield, L. (2001). Evaluation of a short-term group therapy program for children with behavior problems and their parents. Behaviour Research and Therapy, 39, 823–841.
Hoagwood, K. E. (2005). Family-based services in children's mental health: A research review and synthesis. Journal of Child Psychology and Psychiatry, 46, 690
Kazdin, A. E., & Wassell, G. (2000). Therapeutic changes in children, parents, and families resulting from treatment of children with conduct problems. Journal of the American Academy of Child & Adolescent Psychiatry, 39, 414-420.
Kazdin, A. E., & Whitley, M. K. (2003). Treatment of Parental Stress to Enhance Therapeutic Change Among Children Referred for Aggressive and Antisocial Behavior. Journal of Consulting and Clinical Psychology, 71, 504–515.