A. Following adjudication, the court may order a predisposition investigation. The investigation shall include the circumstances, needs, and social history of the child and his family, and also the circumstances surrounding the factual allegations of the petition. It shall also assess whether the child has an established and significant relationship with a parent, grandparent, sibling, or other relative which should be preserved in the best interests of the child. If so, the department shall include in the case plan arrangements for the child’s continuing contact with such individuals while the child is in foster care.B. A written report of the investigation and findings shall be submitted to the court prior to the disposition hearing.