Relatives of an heir to a well-known Chinese teahouse are embroiled in a legal battle over a will his widow says she discovered in a safe months after his death. The document leaves an estate worth $10 million to the late Lai Ho-kai's stepson. But Lai's elder sister, Catherine Lai Lok-yee, and elder brother, Lai Ho-pak, say it is invalid, a probate hearing was told yesterday. Lai, joint heir with his brother to the Tak Yue restaurant in Shanghai Street, Yau Ma Tei, died of a stroke on September 29, 1996. He was 39. His estate comprises shares in the decades-old restaurant and various properties, say solicitors for widow Wong Oi-king and her son, Derek So Nim-cho, 20. Constable Wong, a policewoman, married Lai in December 1993 and took her son, from a previous marriage, to live with them. She told the Court of First Instance that she came across a sealed envelope marked 'important document, not to be mislaid' a few months after Lai's death while clearing out her late husband's safe. Ms Wong said the late millionaire's will was in an envelope. In it he allegedly expressed his decision to treat Mr So as his own son so that he could inherit his estate - either in whole or in part. Constable Wong and Mr So are seeking a declaration on the validity of the document, dated February 6, 1996. The Lai siblings contest the claim, saying that the document is invalid. If Deputy Judge Andrew Cheung Kui-nang upholds the will, the siblings will be excluded from the estate. If it is not upheld, Lai would be deemed to have died without a will - in which case the first $600,000 would go to the widow. She would then get 50 per cent of what remained. The rest would go to the Lai siblings. The hearing continues.