Family Code § 5700.612
ARTICLE 3. Registration and Modification of Child-Support Order of Another State
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 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.