Adopting Teenage Daughter's Baby

Anyone have any advice / comments? 16 yr old daughter to have baby - father choosing to be out of the picture. As grandparents, do we adopt, request guardianship or do nothing at all? Goals are to make sure the baby is covered by reliable health insurance and to guaranty that father will remain out of the picture. If we adopt, what happens when daughter is done with college and has good job and wishes child to come and live with her and her new husband? If we do guardianship does child have to be covered under state insurance and how do we avoid the father being contacted by the state for reimbursement? We feel if father is required to pay anything he may wish to see child at any time and we don't feel it is fair for him to all of the sudden come forward and want visitation. Live in Michgan.