The court shall have power at any time, upon proof that any defendant who has not been served with process has ceased to be an owner since the filing of such petition, to substitute the new owner as a defendant, and after due service of the summons and petition upon him or her proceed as though he or she had been a party in the first instance; and the court may upon any finding of the jury, or at any time during the course of the proceedings, enter every such order, rule, judgment, or decree as the nature of the case may require.
RCW 91.08.220
New parties may be admitted: RCW 91.08.170.
Procedure after findings: RCW 91.08.210.