California Code, Code of Civil Procedure - CCP § 872.530

(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.