N.C. Gen. Stat. § 52C-6-616

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 G.S. 52C-6-601 through G.S. 52C-6-608 if the order has not been registered. A petition for modification may be filed at the same time as a request for registration, or at another time. The petition must specify the grounds for modification.