Md. Code, Family Law § 10–353.2

(a) A party or support enforcement agency seeking to modify, or to modify and enforce, a foreign child support order not under the Convention may register that order in this State under §§ 10–340 through 10–347 of this subtitle if the order has not been registered. A complaint for modification may be filed at the same time as a request for registration, or at another time.

(b) The complaint shall specify the grounds for modification.