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 14-5-601 through 14-5-608 if the order has not been registered. A petition for modification may be filed at the same time as a request for registration, or later. The pleading must specify the grounds for modification.
Procedure to register child support order of another state for modification
Colo. Rev. Stat. § 14-5-609, under Registration, Enforcement, and Modification of Support Order.
Colo. Rev. Stat. § 14-5-609