Rupert Murdoch has failed in his bid to change an irrevocable family trust, a Nevada probate commissioner ruled on Saturday (US time).

The 96-page sealed ruling, obtained by The New York Times, said Murdoch’s attempts to alter the trust, which holds the voting power for both News Corp and Fox News-owner Fox Corp, were done in “bad faith”.

The move was an attempt by the 93-year-old to cement his eldest son Lachlan’s control of the family empire after his death and secure their media assets’ conservative positioning. Rupert Murdoch arrived in Sydney last week and attended Lachlan’s Christmas party on Thursday.

The trust currently would divide control of the company equally among Rupert Murdoch’s four oldest children – Lachlan, James, Elisabeth and Prudence – after his death. Without change, Lachlan’s siblings could effectively remove him from his position of control.

Murdoch’s attempts were only to alter the voting power, rather than the financial share each sibling will receive. His youngest children (from his third marriage), Chloe and Grace, have a financial stake in the trust, however they do not have any voting power.

In his opinion, the commissioner, Edmund J. Gorman Jr, said the plan to change the trust was a “carefully crafted charade” to “permanently cement Lachlan Murdoch’s executive roles” inside the empire “regardless of the impacts such control would have over the companies or the beneficiaries” of the family trust, the Times said.

A lawyer for Rupert Murdoch, Adam Streisand, said they were disappointed with the ruling and intended to appeal, the Times reported.

In a statement provided to the Times, James, Elisabeth and Prudence said: “We welcome Commissioner Gorman’s decision and hope that we can move beyond this litigation to focus on strengthening and rebuilding relationships among all family members.”