D.C. Code § 16-4603.07

If a proceeding for enforcement under this subchapter is commenced in a court of the District and the court determines that a proceeding to modify the determination is pending in a court of another state having jurisdiction to modify the determination under subchapter II of this chapter, the enforcing court shall immediately communicate with the modifying court. The proceeding for enforcement continues unless the enforcing court, after consultation with the modifying court, stays or dismisses the proceeding.