A grandparents' medical consent form allows a parent or legal guardian to hand over all responsibility regarding their child's healthcare decisions. This article contains information on one way that certain nonparents can be allowed to consent to medical treatment of a minor child.How to fill out the Grandparent Medical Consent Form for Minors? This consent form should be taken with the child to the Physician's office when the child is taken for treatment. 1. Enter the child's full name and personal details.