Detailed answer — who must be in a New Mexico partition action and how to add heirs

Short answer: Yes — if your deceased sibling owned an interest in the real property that is the subject of a partition action, the people or entities who succeeded to that interest (typically the personal representative of the decedent’s estate or the decedent’s heirs) must be included in the partition action. To add them you will usually (1) identify who holds the decedent’s interest, (2) join the proper successor(s) of that interest as parties, and (3) give them legal notice or obtain the court’s permission for alternative service if they cannot be found.

Why this matters: A partition action divides property among co-owners or sells the property and divides the proceeds. The court must have jurisdiction over all persons who own an interest in the property so any order fairly determines each owner’s rights. If someone who owns an interest is not joined, a later court order could be incomplete or subject to challenge.

Who to join in New Mexico

• If the deceased owner’s estate is open and a personal representative (executor or administrator) has been appointed in probate, that representative should be joined and served as the party that represents the decedent’s interest.
• If no probate has been opened and the heir(s) are known, New Mexico courts will generally allow the heir(s) (or the successor-in-interest) to be joined directly. If ownership passed by operation of law (intestacy) or by will, the heirs or devisees are the proper successors.
• If there are unidentified or unlocatable heirs, the plaintiff can ask the court for permission to serve by publication or take other alternative service steps so the court can obtain jurisdiction over unknown parties.

Typical steps to add heirs or a personal representative

1. Confirm the chain of title and the decedent’s interest. Search property records and the county assessor’s records to confirm the decedent was an owner and to determine the fractional interest at issue.
2. Check whether a probate case exists. Look at the probate docket in the county where the decedent lived or where the property is located. If a personal representative has been appointed, obtain a certified copy of the Letters Testamentary or Letters of Administration and join that representative as a party. New Mexico court probate information: nmcourts.gov — probate self-help.
3. If there is no probate, identify and locate heirs. If heirs are known, add them as parties in the petition or by motion to join parties. If the heirship is contested, you may need a preliminary determination of heirship through probate or quiet-title procedures.
4. File a motion or an amended pleading to substitute or add parties. In practice you will either (A) name the personal representative or named heirs in your initial partition complaint, or (B) file a motion to substitute parties after the action has begun, attaching proof of the decedent’s death and documentation of who succeeded to the interest (e.g., certified death certificate, probate filings, heirship affidavit, or other proof).
5. Serve proper notice. Serve the added parties with the complaint or the motion according to New Mexico service rules. If a party cannot be located, ask the court for permission to serve by publication or alternative methods. If a party is a minor or legally incapacitated, the court will require appointment of a guardian ad litem to protect that party’s interests.
6. If necessary, open a probate or seek an ancillary probate to establish who the heirs are or to appoint a personal representative to appear in the partition action.

Evidence and proof you will need

• Certified copy of death certificate for the deceased owner.
• Proof of appointment of a personal representative (if probate is open): Letters Testamentary or Letters of Administration.
• Recorded deed or title documents showing the decedent’s ownership interest before death.
• Affidavits of heirship, probate documents, or other records showing who inherited the decedent’s interest.
• Affidavits or receipts showing attempts to locate heirs if you need alternative service.

What if an heir is missing or unknown?

New Mexico courts allow service by publication or other alternative service methods when a party cannot be located, but the court will require a showing that you made reasonable efforts to find the person. If heirs are unknown, the court may permit notice by publication and may appoint a guardian ad litem to protect the interests of unknown or unborn heirs. In some cases a separate probate or heirship proceeding is the best way to establish the identity of heirs before proceeding with partition.

Practical example (hypothetical)

Suppose Sibling A and Sibling B owned equal undivided interests in a parcel. Sibling B died intestate leaving two adult children (Heir 1 and Heir 2). If Sibling A files a partition action, Sibling A must name Heir 1 and Heir 2 (or the personal representative if probate is open) as defendants because they now hold Sibling B’s interest. If Heir 2 cannot be located, Sibling A can ask the court to allow service by publication after demonstrating reasonable search efforts; the court may also require appointment of a guardian ad litem or other protective steps.

Relevant New Mexico resources

• New Mexico Courts — self-help and probate information: https://www.nmcourts.gov/self-help/probate/
• New Mexico statutes and legislative information (search NMSA for statutes on probate and property): https://www.nmlegis.gov/Legislation/Statutes
• New Mexico Rules (check civil and probate procedure rules for substitution, service, and guardian ad litem rules): https://www.nmcourts.gov/rules/

Bottom line: To include heirs of a deceased sibling in a New Mexico partition action you must identify whether a probate has been opened and then join and properly serve the decedent’s successor(s) in interest (personal representative or heirs). If heirs cannot be located or are unknown, follow the court’s procedures for alternative service and for protecting minors or unknown heirs. Because the procedures can be technical and mistakes can affect your rights, consult a New Mexico attorney or the probate clerk in the county where the decedent lived or where the property is located.

Disclaimer: This article provides general information about New Mexico law and common procedures. It is not legal advice, does not create an attorney-client relationship, and may not reflect the most current law. For advice about your specific situation consult a licensed New Mexico attorney.

Helpful hints — quick checklist when adding heirs in a New Mexico partition action

• Start with the recorded deed and property records to confirm ownership and the precise interest at stake.
• Search the local probate docket early — joining a personal representative is often the fastest way to handle a decedent’s interest.
• If no probate exists, prepare affidavits, death certificate, and heirship information before filing or amending your complaint.
• When heirs are hard to find, document your search efforts (addresses, phone calls, online searches) to support a request for service by publication.
• If anyone named as an heir is a minor or incompetent, ask the court to appoint a guardian ad litem to protect that party’s interest in the partition proceeds or property.
• Consider opening a simple probate or judicial determination of heirship if heirship is disputed or unclear — it may simplify the partition action.
• Keep court deadlines and service rules in mind — omission of an owner can lead to delay or reversal of the partition judgment.
• When in doubt, consult with a New Mexico real property or probate attorney who can help with substitutions, service, and protecting your rights in a partition.