Rupert Murdoch is in a secret legal battle pitching the ageing mogul and his heir apparent, Lachlan Murdoch, against three of his other children, according to documents seen by the New York Times. Murdoch, 93, is attempting to secure Lachlan Murdoch’s control of the family’s media empire by changing the terms of a family trust that would have also given younger brother James, sister Elisabeth and half-sister Prudence a say in how the company is run. Currently, the trust would hand control of the billionaire media tycoon’s sprawling empire to his four eldest children when he dies. But according to sealed court documents obtained by the New York Times, Murdoch is arguing that Lachlan should have sole control of the family’s investments in Fox News, the Wall Street Journal, the New York Post, the Australian and other assets, including the Sun and the Times in the UK. Lachlan Murdoch is seen as the most conservative of Murdoch’s children and his father is arguing that his political beliefs are essential to maintaining the value of the right-leaning media company. According to the Times, a Nevada probate commissioner found last month that the family’s irrevocable trust can be rewritten if Murdoch can prove he is acting in good faith to protect the value of the trust’s holdings. His effort to rewrite the trust is being led by William Barr, former US attorney general under George HW Bush and Donald Trump, the Times reported. Unless a resolution is reached, the fight for the future of Fox could go to court in September, just two months before the US election. Murdoch is said to have dubbed the bid “Project Harmony”, based on the belief that it would see off the prospect of a power struggle within the family after his death. But his children were reportedly blindsided by the move. Fox was not immediately available for comment. Lachlan Murdoch became chair of News Corporation and Fox Corporation, the parent company of Fox News, last November after his father made the announcement he was ending his seven-decade run as one of the most transformative – and controversial – media barons in history. James Murdoch had once been seen as a possible successor but has become a vocal critic of the Fox media assets’ denial of climate change. After the January 6 insurrection, James Murdoch criticized the US media for “propagating lies” that unleashed “insidious and uncontrollable forces”. In April 2023, Fox reached a $787.5m settlement with voting equipment company Dominion. It had been accused of knowingly broadcasting false and outlandish allegations that Dominion had been involved in a plot to steal the 2020 election.