California Code
CHAPTER 8 - Compulsory Joinder
Section 389.5.

389.5. When, in an action for the recovery of real or personal property, or to determine conflicting claims thereto, a person not a party to the action but having an interest in the subject thereof makes application to the court to be made a party, it may order him to be brought in by the proper amendment.

(Added by Stats. 1957, Ch. 1498.)