If a child support order issued by a tribunal of the Commonwealth is modified by a tribunal of another state that assumed jurisdiction pursuant to the Uniform Interstate Family Support Act, a tribunal of the Commonwealth:
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 that 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.