Family Code § 5700.711

(a) A tribunal of this state may not modify a Convention child-support order if the obligee remains a resident of the foreign country where the support order was issued unless:

(1) the obligee submits to the jurisdiction of a tribunal of this state, either expressly or by defending on the merits of the case without objecting to the jurisdiction at the first available opportunity; or

(2) the foreign tribunal lacks or refuses to exercise jurisdiction to modify its support order or issue a new support order.

(b) If a tribunal of this state does not modify a Convention child-support order because the order is not recognized in this state, Section 5700.708(c) applies.