RCW 11.96A.220: Binding agreement.

RCW 11.96A.210 through 11.96A.250 shall be applicable to the resolution of any matter, as defined by RCW 11.96A.030, other than matters subject to chapter 11.130 RCW, or a trust for a minor or other incapacitated person created at its inception by the judgment or decree of a court unless the judgment or decree provides that RCW 11.96A.210 through 11.96A.250 shall be applicable. If all parties agree to a resolution of any such matter, then the agreement shall be evidenced by a written agreement signed by all parties. Subject to the provisions of RCW 11.96A.240, the written agreement shall be binding and conclusive on all persons interested in the estate, trust, nonprobate asset, other property passing at death, or custodial property. The agreement shall identify the subject matter of the dispute and the parties. If the agreement or a memorandum of the agreement is to be filed with the court under RCW 11.96A.230, the agreement may, but need not, include provisions specifically addressing jurisdiction, governing law, the waiver of notice of the filing as provided in RCW 11.96A.230, and the discharge of any special representative who has acted with respect to the agreement.

If a party who virtually represents another under RCW 11.96A.120 signs the agreement, then the party's signature constitutes the signature of all persons whom the party virtually represents, and all the virtually represented persons shall be bound by the agreement.