If a child-support order issued by a tribunal of the District is modified by a tribunal of another state which assumed jurisdiction pursuant to the Uniform Interstate Family Support Act, a tribunal of the District:
(1) May enforce its order that was modified only as to arrears and interest accruing before the modification;
(2) May provide appropriate relief for violations of its order which occurred before the effective date of the modification; and
(3) Shall recognize the modifying order of the other state, upon registration, for the purpose of enforcement.