G.R. No. 235033 - Kristine Calubaquib-Diaz vs. Dino Lopez Diaz and Republic

Kristine Calubaquib-Diaz and Dino Lopez Diaz became lovers in 2009 and lived together in Dino’s Angono, Rizal residence, with Kristine primarily supporting household expenses.
Kristine became pregnant and informed Dino through text, but he delayed response and continued his extramarital affairs despite promises to reform.
They married on June 28, 2010, with Kristine’s parents paying wedding expenses; on the wedding night, Dino left Kristine alone and went out with friends.
After the wedding, they lived with Kristine’s parents in Quezon City; Kristine gave birth to their son Duke on November 21, 2010.
Dino neglected marital obligations: he did not support or care for Kristine and Duke, spent time partying and drinking, and depended financially on Kristine and her parents.
Dino’s continued philandering and irresponsible behavior contributed to the dissolution of their relationship by 2012.

Kristine filed a Petition for Declaration of Nullity of Marriage on May 2, 2013, citing Dino’s psychological incapacity pursuant to Article 36 of the Family Code.
Summons issued to Dino was returned unserved after two attempts at the indicated address, with a security guard stating Dino only visited occasionally and resided in Antipolo City.
The Office of the Solicitor General appeared and delegated authority to the City Prosecutor of Quezon City.
Kristine filed a motion for alias summons and leave to serve by publication, which the Regional Trial Court (RTC) granted on August 8, 2013; summons by publication was subsequently issued.
Due to Kristine's failure to comply with requirements, the case was archived on December 27, 2013, but later reinstated by the RTC on February 27, 2014.
The assistant city prosecutor investigated and found no collusion between the parties. Trial proceeded with witnesses supporting Kristine’s petition.
RTC rendered judgment declaring the marriage null and void on grounds of psychological incapacity, awarding custody of the minor child to Kristine.
The Office of the Solicitor General moved for reconsideration, which was denied by the RTC.

On appeal, the Court of Appeals (CA) reversed the RTC decision for lack of jurisdiction over Dino, citing defects in summons service.
CA observed that the process server did not sufficiently attempt personal service or substituted service and that Dino’s known residence was not adequately pursued.
Kristine moved for reconsideration, which CA denied.
Kristine filed a Petition for Review with the Supreme Court, arguing that summons by publication was proper given respondent’s elusiveness and that jurisdiction over the res vested the RTC with authority.
Petitioner claimed that the Office of the Solicitor General is estopped from questioning jurisdiction for failing to oppose summons by publication at an earlier stage.

Whether summons was validly served upon respondent Dino Lopez Diaz through publication, thereby conferring jurisdiction on the RTC over his person.
Whether the Office of the Solicitor General is estopped from questioning the jurisdiction of the RTC over respondent’s person because it did not oppose the motion to serve summons by publication early in the proceedings.