Maryland Code, Estates and Trusts § 1-208

(1) The individual has been judicially determined to be the child's parent in an action brought under Title 5, Subtitle 10 of the Family Law Article, and that determination has not been modified or set aside;

(2) The individual and the child's mother consented to the conception of the child by means of assisted reproduction with the shared express intent to be the parents of the child, subject to the conditions under § 1-205(a)(2) of this subtitle if the child is conceived after the death of the individual; or

(3) The child's mother identifies the individual as the other biological parent of the child and the individual agrees.

(1) Has acknowledged himself or herself, in writing, to be a parent of the child;

(2) Has openly and notoriously recognized the child to be the individual's child; or

(3) Has subsequently married or registered a domestic partnership with the mother and has acknowledged himself or herself, orally or in writing, to be a parent of the child.