A party or support enforcement agency seeking to modify, or to modify and enforce, a child support order issued in another state shall register that order in this state in the same manner provided in Sections 40-6A-601 through 40-6A-608 N.M. Stat. Ann. if the order has not been registered. A petition for modification may be filed at the same time as a request for registration, or later. The pleading shall specify the grounds for modification.