If a child-support order issued by a tribunal of this State is modified by a tribunal of another state which assumed jurisdiction pursuant to the Uniform Interstate Family Support Act, a tribunal of this State:
1. May enforce the 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.