(a) Joint owners shall file a joint application by signing as joint applicants.

(b) If an application for certificate is made by two or more persons as joint owners, when they were not in fact joint owners, the application shall be amended prior to issuance of a certificate by filing a corrected application, together with a written explanation signed by the original applicants. Such statement shall also be signed by the assignee, if any.

(c) If an application has been made by less than all the actual joint owners, the application shall be amended by filing a corrected application, together with a written explanation, signed by all of the joint owners. Such statement shall also be signed by the assignee, if any.

(d) If a joint owner refuses to join in an application or cannot be found after diligent effort, the remaining owner may file an application on behalf of him or herself and the missing owner. Such application shall be accompanied by a written explanation and shall state the last known address of the missing owner. Notice of the filing of the application shall be forwarded by the Office to the missing owner at the last known address. If such notice is returned to the Office undelivered, or if the address of the missing owner is unknown, notice of the filing of the application shall be published once on the Plant Variety Protection Office website (https://www.ams.usda.gov/PVPO). Prior to the issuance of the certificate, a missing owner may join in an application by filing a written explanation. A certificate obtained by fewer than all of the joint owners under this paragraph conveys the same rights and privileges to said owners as though all of the original owners had joined in an application.