Md. Code, Family Law § 5–3A–13

(a) Only a child placement agency may petition for guardianship under this subtitle.

(b) A court may grant guardianship under this subtitle only for a minor.

(c) A petitioner shall attach to a petition:

(1) all written consents for the guardianship that the petitioner has; and

(2) if applicable:

(i) proof of guardianship or relinquishment of parental rights granted by an administrative, executive, or judicial body of a state or other jurisdiction; and

(ii) certification that the guardianship or relinquishment was granted in compliance with the jurisdiction’s laws.