Maryland Family Law Section 9.5-202

      (a)      Except as otherwise provided in § 9.5-204 of this subtitle, a court of this State that has made a child custody determination consistent with § 9.5-201 or § 9.5-203 of this subtitle has exclusive, continuing jurisdiction over the determination until:

            (1)      a court of this State determines that neither the child, the child and one parent, nor the child and a person acting as a parent have a significant connection with this State and that substantial evidence is no longer available in this State concerning the child's care, protection, training, and personal relationships; or

            (2)      a court of this State or a court of another state determines that the child, the child's parents, and any person acting as a parent do not presently reside in this State.

      (b)      A court of this State that has made a child custody determination and does not have exclusive, continuing jurisdiction under this section may modify that determination only if it has jurisdiction to make an initial determination under § 9.5-201 of this subtitle.