Heirs of Spouses Silvestre Manzano and Gertrudes D. Manzano, Represented by Conrado D. Manzano as Attorney-in-Fact and Also in His Personal Capacity, Petitioners vs. Kinsonics Philippines, Inc., Respondent

The Court held that an administrator of an intestate estate is not an indispensable party to a civil action for specific performance and/or sum of money involving property allegedly belonging to the decedent's conjugal partnership; at most, such administrator constitutes a necessary party whose interest is separable from the immediate contractual dispute. The Court further ruled that parties are barred by estoppel and unclean hands from raising new substantive or procedural issues for the first time on appeal after failing to plead them below and after profiting from the transaction under scrutiny.

On July 19, 1993, the parties executed a Contract to Sell over a 35,426-square-meter parcel of land in Barangay Lias, Marilao, Bulacan, for a total contract price of P23,026,900.00. The respondent, as vendee, paid P8,000,000.00 by January 27, 1995, and incurred P700,000.00 in expenses to convert the property's classification from agricultural to industrial. When the respondent tendered the remaining balance in February and March 1995, the petitioners refused acceptance, asserting that the 60-day payment period stipulated in the contract had expired following the approval of the land conversion on November 25, 1994. The petitioners maintained that the contract had been automatically rescinded pursuant to its terms.

• The respondent paid P8,000,000.00 of the contract price and incurred P700,000.00 for land conversion expenses prior to tendering the remaining balance in early 1995.
• The petitioners refused the tendered payments, contending that the contractual payment period had lapsed following the land conversion approval on November 25, 1994, and that the contract was automatically rescinded under its terms.
• The respondent filed a complaint for specific performance and/or sum of money, praying for the execution of a deed of absolute sale, or alternatively, the return of payments with interest, plus damages.
• The trial court denied the respondent's motion for summary judgment, which the CA reversed via certiorari, granting summary judgment in favor of the respondent and remanding the case solely for the determination of damages.
• The Supreme Court affirmed the CA's summary judgment ruling in a 2003 resolution that attained finality.
• On remand, the trial court awarded attorney's fees and exemplary damages after the respondent presented its evidence-in-chief and the petitioners failed to appear despite notice.
• On appeal, the petitioners raised three new theories: the trial court proceedings were null and void for failure to implead the estate administrator; the disposition of conjugal property was void under Article 130 of the Family Code for lack of prior liquidation; and genuine issues of fact in their Answer warranted a full trial rather than summary judgment.
• The CA affirmed the trial court's judgment but deleted the exemplary damages award, ruling that compensatory damages are a prerequisite for exemplary damages. The CA also held that the new issues could not be raised for the first time on appeal and that the summary judgment was already final and executory.

• Petitioner maintained that the trial court's failure to implead the administrator of the estates/conjugal partnership of the deceased spouses rendered all subsequent proceedings and the resulting judgment null and void for lack of jurisdiction.
• Petitioner argued that the disposition of the subject parcel was void under Article 130 of the Family Code, which mandates the liquidation of conjugal partnership property before any disposition or encumbrance upon the termination of marriage by death.
• Petitioner contended that their Answer raised genuine issues of material fact that precluded summary judgment and required a full trial on the merits.

• Respondent countered that the petitioners' new issues were never raised in their Answer or during the trial court proceedings, and are therefore barred from being raised for the first time on appeal.
• Respondent asserted that the CA's 2003 summary judgment ruling attained finality and executory status in 2003, rendering it immutable and unalterable.
• Respondent argued that petitioners are barred by estoppel and the doctrine of clean hands from challenging the validity of the contract and proceedings after actively participating in the transaction, receiving payments, and litigating the case for decades.

• Procedural Issues: Whether the issue of the non-joinder of the estate administrator can be raised for the first time on appeal, and whether petitioners are barred by estoppel from introducing new theories at this stage of the proceedings.
• Substantive Issues: Whether the administrator of the estates/conjugal partnership of the deceased spouses constitutes an indispensable party to a civil action for specific performance and/or sum of money concerning a parcel of land allegedly covered by the decedents' estate.

• Procedural: The Court ruled that petitioners are barred by estoppel from raising new theories on appeal. Because the petitioners submitted to the trial court's jurisdiction by filing an Answer that omitted the alleged nullity of the contract, and because they profited from the transaction, equity precludes them from performing an about-face to evade liability. The Court emphasized that issues not pleaded below violate due process and fair play, and the petitioners' belated invocation of jurisdictional defects cannot retroactively invalidate proceedings where no patent lack of jurisdiction appears on the face of the judgment.
• Substantive: The Court held that the estate administrator is not an indispensable party to the complaint. At most, the administrator qualifies as a necessary party under Section 8, Rule 3 of the Rules of Court, as their interest in the property is separable from the immediate contractual obligations between the vendee and the heirs/attorney-in-fact. The absence of a duly appointed administrator does not divest the trial court of jurisdiction, particularly where no probate proceedings had been instituted. The Court noted that a future administrator retains independent remedies, such as an action for annulment of judgment or declaration of nullity, to protect the estate's interests without invalidating the present adjudication between the contracting parties.

• Rule on Compulsory Joinder of Indispensable Parties — Section 7, Rule 3 of the Rules of Court defines indispensable parties as those without whom no final determination of an action can be had. The Court clarified that an estate administrator is merely a necessary party in contractual disputes over decedent property, as their interest is separable and does not bar the court from adjudicating the immediate rights and obligations of the contracting parties. The non-joinder of a necessary party does not deprive the court of jurisdiction or render the judgment void.
• Estoppel and the Doctrine of Clean Hands — Parties are barred from raising new issues on appeal that were not pleaded in the lower court, particularly when they have actively participated in the contract and litigation and derived benefit therefrom. The Court applied the equitable principle that a litigant who comes to court with unclean hands—by profiting from a transaction and later attempting to evade liability through belated jurisdictional attacks—shall be denied relief.

• "The absence of an indispensable party renders all subsequent actuations of the court null and void, for want of authority to act, not only as to the absent parties, but even as to those present." — The Court cited this established principle to delineate the strict consequences of non-joinder, but distinguished it from the present case where the administrator's absence did not affect the court's authority over the contracting parties.
• "By submitting to the jurisdiction of the trial court vis-à-vis their filing of an Answer that did not raise the nullity of the Contract to Sell itself, and by actually profiting from the transaction that they now question, petitioners cannot now perform an about-face and attempt to evade liability." — This passage underscores the application of estoppel and unclean hands, emphasizing that a party's prior conduct and litigation strategy preclude belated challenges to proceedings that have already attained finality.

• Uy v. Court of Appeals — Cited to define the stringent requirements for indispensable parties and to establish that their absence voids court proceedings, thereby providing the baseline against which the Court distinguished the estate administrator's status.
• Chua Tan v. Del Rosario — Cited to delineate the statutory powers, duties, and representative capacity of an estate administrator over decedent property for settlement and inventory purposes.
• Corpuz v. Corpuz — Cited to explain the statutory rule under Act No. 3176 and the Family Code that dispositions of conjugal property without prior liquidation are void, though distinguished here due to the petitioners' failure to attach proof of the contract's nullity to the record.
• Co v. Court of Appeals — Cited for the rule that a collateral attack on a judgment is proper only when the nullity is patent on the face of the judgment, such as a clear lack of jurisdiction.
• Imani v. Metropolitan Bank & Trust Co. — Cited to firmly establish that raising new theories, issues, or arguments for the first time on appeal is barred by estoppel and violates due process.
• University of the Philippines v. Catungal, Jr. and Asian Transmission Corp. v. Commissioner of Internal Revenue — Cited to apply the doctrine of clean hands, holding that equity denies relief to litigants whose conduct has been inequitable or who attempt to benefit from their own prior omissions and misrepresentations.

• Section 7 and Section 8, Rule 3 of the 1997 and 2019 Rules of Civil Procedure — Governs the compulsory joinder of indispensable parties and the permissive joinder of necessary parties, respectively. The Court applied these provisions to classify the estate administrator as a necessary, not indispensable, party.
• Section 3, Rule 84 of the 1997 Rules of Court — Grants an executor or administrator the right to possession and management of the decedent's real and personal estate for debt payment and administration, establishing the scope of the administrator's authority over the subject property.
• Article 130 of the Family Code (Executive Order No. 209) — Mandates the liquidation of conjugal partnership property upon termination of marriage by death and declares void any disposition or encumbrance made without prior liquidation. The Court acknowledged the provision but found it inapplicable on the record due to the petitioners' failure to substantiate their claims.