Detailed answer

Short answer: Yes. In California partition actions the court has tools to protect the interests of owners or heirs who are unknown or unlocatable. The court can require a party to show diligent efforts to find them, allow substituted service (often by publication), and—when necessary—appoint a guardian ad litem (GAL) or other court representative to protect the missing owners’ interests.

Why this matters: A partition action divides or sells property when co-owners disagree. Because partition decrees bind all persons with an interest in the property, the court must take steps to give legally sufficient notice and representation to anyone affected, even if their identity or whereabouts are unknown.

Statutory and procedural foundations

• Appointment of a guardian ad litem for persons who cannot adequately represent themselves (for example minors, persons of unsound mind, or parties who are not before the court) is authorized by the Code of Civil Procedure. See Code of Civil Procedure section 372 for appointment authority and role: Cal. Code Civ. Proc. § 372.
• If you cannot personally serve a named party because their location is unknown, California permits substituted service by publication in some cases, after the court is satisfied that diligent efforts were made to locate the person. See the statutes governing service and substituted service, including Code of Civil Procedure section 415.50: Cal. Code Civ. Proc. § 415.50.
• Partition actions themselves are controlled by the Code of Civil Procedure (the partition chapters). Courts combine the partition statutes, the service rules, and the GAL appointment rules to ensure missing owners are represented and bound only after proper procedures are followed.

How courts typically proceed (practical steps)

1. Requirement of a thorough search: Before the court will let you proceed against an unknown or unlocatable owner, you must show reasonable diligence—title searches, public records checks, contacting known relatives, and any other reasonable steps. The court looks for good-faith efforts to identify or locate the person before allowing substituted service or appointing a GAL.
2. Request substituted service if necessary: If the person can’t be personally served, you can ask the court to allow service by publication or other substituted service. That step requires a declaration of due diligence and specific factual showing. Publication is not automatic; the court must find that personal service isn’t reasonably practical.
3. Ask the court to appoint a guardian ad litem (or other representative): When the court determines an owner is unknown, a GAL can be appointed to protect that owner’s interest during the litigation. The GAL’s job is limited: investigate, defend the interests of the absent owner, and take positions in the action that are reasonably calculated to protect the absent owner.
4. Approval of settlements, sales, or distributions: If the partition results in a sale or a division of proceeds, the court will carefully review any proposal that affects interests of persons not personally before the court. The GAL must often approve settlements on behalf of the absent owner, or the court will order how proceeds are held or distributed (for example, deposited with the court or placed in a blocked account) pending later claims.
5. Fees and bonding: The GAL may be an attorney appointed to represent the absent owners. The court may require a bond or provide that the GAL’s fees come from sale proceeds or from the appointing party, depending on the order the court issues.

Limitations and practical considerations

• Appointment is discretionary. The court will appoint a GAL only when necessary to protect interests and when statutory requirements are met.
• A GAL does not create new rights. The GAL represents the absent owner’s existing legal interest; the GAL cannot concede or create rights outside that scope without court approval.
• If a formerly unlocatable heir later appears, that person can assert rights subject to what the court already ordered. The court’s prior orders are controlled by due notice and proper representation rules—procedural defects can sometimes be challenged, but not automatically.

Typical documents and motions you’ll need

• Declaration of due diligence describing steps taken to locate the missing owner.
• Motion (or noticed request) for substituted service by publication, with proposed notice language and a publication plan.
• If relevant, a motion to appoint a guardian ad litem (or application asking the court to appoint counsel to represent unknown owners) and a proposed order setting the GAL’s duties and compensation.
• Proposed orders for how sale proceeds or distributive shares will be handled for missing owners (e.g., deposit to court, blocked account, or bond).

Helpful Hints

• Start with a thorough title and probate search. Records often show heirs, prior addresses, or probate matters that reveal likely heirs.
• Document every step you take to find an heir. Courts require a factual showing of due diligence before allowing substituted service or appointing a GAL.
• Consider hiring counsel experienced in partition and quiet-title work. These cases combine real property, procedural, and occasionally probate issues.
• Expect the court to require reasonable protections for missing owners’ money—either bonded deposits, blocked accounts, or an appointed representative with court-approved fees.
• If you locate a likely heir, serve them personally if possible. Personal service avoids the extra time, expense, and uncertainty of publication and GAL proceedings.
• If the missing person is a minor or appears to be incapacitated, ask the court to appoint a GAL specifically under Cal. Code Civ. Proc. § 372 so the minor’s or incapacitated person’s statutory protections apply: Cal. Code Civ. Proc. § 372.
• When you request substituted service, follow the requirements of the service statutes—publication alone is not enough without the court’s prior authorization. See Cal. Code Civ. Proc. § 415.50 for substituted service procedures: Cal. Code Civ. Proc. § 415.50.