Wash. Rev. Code § 8.12.150
If the land and buildings belong to different parties, or if the title to the property be divided into different interests by lease or otherwise, the damages done to each of such interests may be separately found by the jury on the request of any party. In making such findings, the jury shall first find and set forth in their verdict the total amount of the damage to said land and buildings and all premises therein, estimating the same as an entire estate and as if the same were the sole property of one owner in fee simple; and they shall then apportion the damages so found among the several parties entitled to the same, in proportion to their several interests and claims and the damages sustained by them respectively, and set forth such apportionment in their verdict. No delay in ascertaining the amount of compensation shall be occasioned by any doubt or contest which may arise as to the ownership of the property, or any part thereof, or as to the extent of the interest of any defendant in the property to be taken or damaged, but in such case, the jury shall ascertain the entire compensation or damage that should be paid for the property and the entire interests of all the parties therein, and the court may thereafter require adverse claimants to interplead, so as to fully determine their rights and interests in the compensation so ascertained. And the court may make such order as may be necessary in regard to the deposit or payment of such compensation.
RCW 8.12.150
Rules of court: CR 54.