This article from NACAC describes the 3-5-7 Model used to treat children and youth.

The 3-5-7 Model is designed to help professionals and parents work with children and youth to address these issues of grief and loss. It is an evidenced-informed, guided practice approach that supports the work of children and parents in grieving their losses and rebuilding their relationships in an effort to achieve well-being, safety, and permanency. The model incorporates theoretical underpinnings from child development, attachment, separation and loss, trauma, family systems, and relationship development.