The younger brother of late Nina Wang Kung Yu-sum, Dr Kung Yan-sum, could become more involved in the business of Chinachem Group and its charitable foundation after he retires from his clinic this week. His plans to retire from his 30 years of practice started before the probate litigation that began in May this year, according to a person close to the situation. But Kung did not set out to close down his clinic in order to become more involved in the business of the group and the foundation, the South China Morning Post was told. 'Dr Kung has always been a director of the group and he comes to the office every morning, anyway. He is now in his 70s. He began telling his patients even before the trial that they could not expect him to continue his clinic work for the rest of his life,' the person said. But the parties involved have agreed that Kung's retirement will involve spending more time closely managing the business left by his late tycoon sister. The Post has not learned why Dr Kung chose to close the clinic now - Thursday will be its final day. The judge's ruling on his sister's will is due to be delivered by the end of this year or early next year. Wang's sister, Dr Molly Gong Chung-sum, will continue her role in Chinachem Group overseeing its marketing business. She had moved back to Hong Kong before the litigation began, from her research post in the United States. Her husband has recently taken a research job at a local university and has decided to settle down with his wife in the city. The Kung siblings led the legal battle against a rival claim, launched by fung shui master Tony Chan Chun-chuen, to control the tycoon's empire. The case was heard in the Court of First Instance before Mr Justice Johnson Lam Man-hon, who is expected to give his judgment probably after Christmas. During Christmas, in addition to Kung's clinic closing down, Chinachem will move its headquarters from Tsim Sha Tsui's Chinachem Golden Plaza to Nina Tower in Tsuen Wan. It had reportedly always been Wang's intention to make Nina Tower the headquarters of Chinachem when the office was built, the person said. It had nothing to do with recent rumours that the move to Tsuen Wan was to cut off any connection to the location where Chan claimed his version of the disputed will was written, he said. It was understood that Wang's former living quarters on the top floor of the Tsim Sha Tsui building would remain untouched, preserved by her family as a memorial. It is also being preserved in case any of its contents might be needed in a future court action. Many of the items that were kept there have been mentioned in the legal battle.