California Codes, Code of Civil Procedure - CCP, Part 2 — Of Civil Actions, Title 10.5 — Partition of Real and Personal Property, Chapter 2 — Commencement of Action, Article 4 — Parties, Section 872.530

(a) If a person described in Section 872.510 is dead and the plaintiff knows of a personal representative, the plaintiff shall join such personal representative as a defendant.

(b) If a person described in Section 872.510 is dead, or is believed by the plaintiff to be dead, and the plaintiff knows of no personal representative:

(1) The plaintiff shall state these facts in an affidavit filed with the complaint.

(2) Where it is stated in the affidavit that such person is dead, the plaintiff may join as defendants “the testate and intestate successors of ____ (naming such deceased person), deceased, and all persons claiming by, through, or under said decedent,” naming them in that manner.

(3) Where it is stated in the affidavit that such person is believed to be dead, the plaintiff may join such person as a defendant, and he may also join “the testate and intestate successors of ____ (naming such person) believed to be deceased, and all persons claiming by, through, or under such person,” naming them in that manner.