Md. Code Ann., Est. & Trusts § 13.5-401

If a guardian has not been appointed in this State and a petition for the appointment of a guardian is not pending in this State, a guardian appointed in another state, after giving notice to the appointing court of an intent to register, may register the guardianship order in this State by filing, as a foreign judgment in a court in any appropriate county of this State, certified copies of the order and letters of office.