Stepmother seeks entire W1.5b estate after 5-year live-in relationship, leaving siblings bereft

A brother and sister who called their father's common-law partner "mother" and treated her with respect were left devastated after learning their father had left his entire estate to her.

The siblings' story was shared Wednesday on YTN Radio's "Attorney Jo In-seop's Consultation" — a dispute over a notarized will their father left behind, pitting them against his common-law partner.

The person who submitted the story said their mother had died of a chronic illness 10 years ago, and that their father, who had been living alone since, met an elementary school classmate five years ago and began living with her.

The father and his former elementary school classmate lived together as a common-law couple, never formally registering their marriage.

According to the account, the father had spent his career as a precision machinery engineer and was a man of few words, so his children had assumed he preferred living alone. The stepmother told them he was actually quite lonely despite not showing it outwardly. The person said the revelation was bittersweet — painful to hear, yet genuinely heartening to know their father was no longer spending his final years in solitude.

The trouble began when the father died suddenly in an accident. As the siblings were still reeling from grief, they discovered a shocking fact: their father had left a notarized will bequeathing his entire estate to the stepmother, including a commercial building worth 1.5 billion won ($983,000).

"Our names were not mentioned even once in that will," the person said. "She says the property was given to her voluntarily by our father and that there is no legal problem, and she intends to take the entire building." The person added, "I understand a hundred times over that our father must have done it out of gratitude toward her, but as his children, we just feel utterly hollow."

The person also asked whether it was even legally possible for a common-law partner — someone who never registered the marriage — to take everything their father owned, and whether there was any way to reclaim their rights.

Attorney Shin Jin-hee said that under civil law, a common-law spouse has no legal inheritance rights, meaning that had the father left no will, the estate would have passed to the children. However, she said, a bequest through a will can be made to any third party, including a common-law partner, and as long as the father followed proper legal procedures, the bequest is in principle valid and the common-law partner is entitled to receive the property.

On cases like this one — where a will transfers the entire estate to a specific individual — Shin said the children, as legal heirs, are entitled to a "forced share," a guaranteed minimum portion of the inheritance. She said the siblings could file a forced-share return claim to recover a portion of the estate from the common-law partner.

She added that while children's legal inheritance shares are divided equally according to the number of heirs, the forced share amounts to half of each heir's statutory share. In this case, she said, each of the two children could claim one-quarter of the total estate from the common-law partner.

Shin cautioned that a forced-share return claim must be filed within one year from the date the claimant learns of the commencement of the inheritance and of the bequest or gift subject to return. "Once this period lapses, the right is extinguished, so legal action must be prepared without delay," she said.

In addition, she noted that any "contribution share" — the portion attributable to the common-law partner's contribution to maintaining or building the estate — would be excluded from the forced-share return calculation.

On the question of what qualifies as a contribution share, Shin said what matters is support or contribution to asset formation that clearly exceeds the level ordinarily expected in a family relationship. "To have a contribution recognized, one must sufficiently prove that it constitutes a special contribution beyond the general standard," she said.