CA Civ Proc Code Section 762.060

(a)

In addition to the persons required to be named as defendants in the action, the plaintiff may name as defendants “all persons unknown, claiming any legal or equitable right, title, estate, lien, or interest in the property described in the complaint adverse to plaintiff’s title, or any cloud upon plaintiff’s title thereto,” naming them in that manner.

(b)

In an action under this section, the plaintiff shall name as defendants the persons having adverse claims that are of record or known to the plaintiff or reasonably apparent from an inspection of the property.

(c)

If the plaintiff admits the validity of any adverse claim, the complaint shall so state.