Md. Code, Family Law § 5–204

(a) (1) If a minor child has only 1 parent, the domicile of the child is the same as that of the parent.

(2) If the parents of a minor child live together, and the child lives with them, the domicile of the child is the same as that of the parents.

(b) If the parents of a minor child live apart, the domicile of the child is the same as that of:

(1) the parent to whom custody is awarded; or

(2) if custody has not been awarded, the parent with whom the child lives.

(c) If a minor child does not live with either parent, the domicile of the child is the same as that of the person who acts in the capacity of a parent.