Wash. Rev. Code § 26.26A.450
(2) If a child has an adjudicated parent, the following rules apply to a proceeding to challenge the adjudication of parentage brought by an individual, other than the child, who has standing under RCW 26.26A.405 and was not a party to the adjudication and did not receive notice under RCW 26.26A.410:
[ 2018 c 6 s 511.]