Washington Revised Code Title 11. Probate and Trust Law § 11.12.091. Omitted child

(1) If a will fails to name or provide for a child of the decedent who is born or adopted by the decedent after the will's execution and who survives the decedent, referred to in this section as an “omitted child,” the child must receive a portion of the decedent's estate as provided in subsection (3) of this section, unless it appears either from the will or from other clear and convincing evidence that the failure was intentional.

(2) In determining whether an omitted child has been named or provided for, the following rules apply:

(3) The omitted child must receive an amount equal in value to that which the child would have received under RCW 11.04.015 if the decedent had died intestate, unless the court determines on the basis of clear and convincing evidence that a smaller share, including no share at all, is more in keeping with the decedent's intent. In making the determination, the court may consider, among other things, the various elements of the decedent's dispositive scheme, provisions for the omitted child outside the decedent's will, provisions for the decedent's other children under the will and otherwise, and provisions for the omitted child's other parent under the will and otherwise.

(4) In satisfying a share provided by this section, the bequests made by the will abate as provided in chapter 11.10 RCW.