MGL c.201F provides a mechanism for parents to authorize a caregiver to make educational and health decisions for their children: the Caregiver Authorization Affidavit. A caregiver is defined as "an adult with whom a minor resides," and there are, of course, many reasons why a parent may need their children to live with someone else for a period of time. The authorization is good for up to two years (you specify the time period) and does not have to be filed with the court. Also, it does not affect the parent's rights to make decisions for the child. In fact, if the decisions of the caregiver and parent conflict, the parent's decision will "supersede the decision of the caregiver."
The Massachusetts Probate and Family Court provides directions for filling out the form, and you can read more about its uses at the Massachusetts Estate Planning, Probate and Elder Law blog, Mass. Legal Help's Caregiver Educational and Medical Authorization, and the Department of Education, which provides helpful information for schools on how to manage caregiver authorizations. You'll find a link to the form on our website as well.