Oregon Revised Statutes Miscellaneous Matters Related to Government and Public Affairs § 198.770

(1) In examining a petition required or permitted to be signed by landowners, the county assessor shall disregard the signature of a person not shown as owner on the last equalized assessment roll unless prior to certification the county assessor is furnished with written evidence, satisfactory to the county assessor, that the signer:

(2) If a person signing a petition as a landowner appears as owner on the last equalized assessment roll but is shown thereon as a partner, tenant in common or tenant by the entirety, the signature of the person signing shall be counted as if all other owners, as shown on the roll for the same parcel of land, had signed.