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 the commonwealth in the same manner provided in sections 6-601 to 6-608, inclusive, if the order has not been registered. A petition or comparable pleading for modification may be filed at the same time as a request for registration or later. The pleading must specify the grounds for modification.
Mass. Gen. Laws ch. 209D, § 6-609