The following persons, who desire to adopt any person or persons over 18 years of age, shall file a petition in the Family Court of the county in which any of the petitioner(s) or the person(s) to be adopted resides:
(1) Any person petitioning individually;
(2) A married couple petitioning jointly; or
(3) A nonmarried couple petitioning jointly, provided that they are cohabiting, as that term is defined in § 1512(g) of this title.