So the part you left out was that this isn't just about school, but that the child is with mom in another state and mom intends to keep custody of the child with her in another state at the end of the summer? That's a gargantuan omission from the facts. All the more reason to seek a custody order, ASAP.
In Maryland, by statute, both parents are the natural guardians of their child. Md. Family Law Code, Sec. 5-203. "Neither parent is presumed to have any right to custody that is superior to the right of the other parent."

