D.C. Code § 16-4602.03
Jurisdiction to modify determination.
Except as otherwise provided in § 16-4602.04 , a court of the District may not modify a child-custody determination made by a court of another state unless a court of the District has jurisdiction to make an initial determination under § 16-4602.01(a)(1) or (2) and:
(1) The court of the other state determines it no longer has exclusive, continuing jurisdiction under § 16-4602.02 or that a court of the District would be a more convenient forum under § 16-4602.07 ; or
(2) A court of the District or a court of the other state determines that the child, the child’s parents, and any person acting as a parent do not presently reside in the other state.