California Code, Family Code - FAM § 7882

(a) If the parent of the child or a person alleged to be or claiming to be the parent cannot, with reasonable diligence, be served as provided for in Section 7881, or if the parent's place of residence is not known to the petitioner, the petitioner or the petitioner's agent or attorney shall make and file an affidavit stating the name of the parent or alleged parent and their place of residence, if known to the petitioner, and the name of the parent or alleged parent whose place of residence is unknown to the petitioner.

(b) Upon the filing of the affidavit, the court shall make an order that (1) the service shall be made by the publication of a citation requiring the parent or alleged parent to appear at the time and place stated in the citation and (2) the citation shall be published pursuant to Section 6064 of the Government Code in a newspaper to be named and designated in the order as most likely to give notice to the parent or alleged parent to be served.

(c) In case of publication where the residence of a parent or alleged parent is known, the court shall also direct a copy of the citation to be forthwith served upon that parent or alleged parent by mail by deposit in the post office properly addressed and with the postage thereon fully prepaid, directed to that parent or alleged parent at the place of residence. When publication is ordered, service of a copy of the citation in the manner provided for in Section 7881 is equivalent to publication and deposit in the post office.

(d) If one or both of the parents of the child are unknown or if the names of one or both of the child's parents are uncertain, that fact shall be set forth in the affidavit and the court shall order the citation to be directed to either or both of the child's parents, naming and otherwise describing the child, and to all persons claiming to be a parent of the child.

(e) Service is complete at the expiration of the time prescribed by the order for publication or when service is made as provided for in Section 7881, whichever event first occurs.