2011 ORS § 105.215¹
Complaint

The interest of all known and unknown persons in the property shall be specifically and particularly set forth in the complaint for partition, as far as known to the plaintiff. If one or more of the parties, or the share or quantity of interest of any of the parties, is unknown to the plaintiff or is uncertain or contingent, or if the ownership of the inheritance depends upon an executory devise, or the remainder is a contingent remainder, so that the parties cannot be named, that fact shall be set forth in the complaint.