Haw. Rev. Stat. § 583A-305: Registration of child-custody determination.

(a) A child-custody determination issued by a court of another state may be registered in this State, with or without a simultaneous request for enforcement, by sending to the appropriate court in this State:

(1) A letter or other document requesting registration;

(2) Two copies, including one certified copy, of the determination sought to be registered, and a statement under penalty of perjury that to the best of the knowledge and belief of the person seeking registration the order has not been modified; and

(3) Except as otherwise provided in section 583A-209, the name and address of the person seeking registration and any parent or person acting as a parent who has been awarded custody or visitation in the child-custody determination sought to be registered.

(b) On receipt of the documents required by subsection (a), the registering court shall cause the determination to be filed as a foreign judgment, together with one copy of any accompanying documents and information, regardless of their form.