A grandparents' medical consent form allows a parent or legal guardian to hand over all responsibility regarding their child's healthcare decisions. Ensure your child's well-being with our easy-to-use child medical consent form.How to fill out the Grandparent Medical Consent Form for Minors? This affidavit is sufficient to authorize the grandparent signing to exercise care, physical custody, and control of the child who is its subject. Click on the link(s) for the forms you'd like to download.