(1) 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:

(a) A letter or other document requesting registration;

(b) 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 determination has not been modified; and

(c) Except as otherwise provided in RCW 26.27.281, 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.

(2) On receipt of the documents required by subsection (1) of this section, the registering court shall:

(a) Cause the determination to be filed as a foreign judgment, together with one copy of any accompanying documents and information, regardless of their form; and

(b) Serve notice upon the persons named pursuant to subsection (1)(c) of this section and provide them with an opportunity to contest the registration in accordance with this section.

(3) The notice required by subsection (2)(b) of this section must state that:

(a) A registered determination is enforceable as of the date of the registration in the same manner as a determination issued by a court of this state;

(b) A hearing to contest the validity of the registered determination must be requested within twenty days after service of notice; and

(c) Failure to contest the registration will result in confirmation of the child custody determination and preclude further contest of that determination with respect to any matter that could have been asserted.

(4) A person seeking to contest the validity of a registered determination must request a hearing within twenty days after service of the notice. At that hearing, the court shall confirm the registered determination unless the person contesting registration establishes that:

(a) The issuing court did not have jurisdiction under Article 2;

(b) The child custody determination sought to be registered has been vacated, stayed, or modified by a court having jurisdiction to do so under Article 2; or

(c) The person contesting registration was entitled to notice, but notice was not given in accordance with the standards of RCW 26.27.081, in the proceedings before the court that issued the determination for which registration is sought.

(5) If a timely request for a hearing to contest the validity of the registration is not made, the registration is confirmed as a matter of law and the person requesting registration and all persons served must be notified of the confirmation.

(6) Confirmation of a registered determination, whether by operation of law or after notice and hearing, precludes further contest of the determination with respect to any matter that could have been asserted at the time of registration.