The legacy of the “happiest place on Earth” has proved, in the end, bitter for a pair of scions of the Walt Disney family.

As the new year dawned, Disney’s twin grandchildren were bracing for the next battle in a legal war of attrition over their stakes in an inheritance estimated to be worth about $400 million.

According to terms of a trust set up by Disney’s late daughter, Sharon Disney Lund, her son and daughter Brad and Michelle Lund are due to get the third and final installment of their inheritance when they turn 45 on June 5.

But the twins – who have nothing to do with the running of the corporate empire – have been feuding for years and continue, through their lawyers, to dispute each other’s mental competence and entitlement to the money.

While Michelle has received other big payments willed to her, Brad has missed out on millions and is determined for things to be different as their bitter and long-running financial fight moves into a key stage.

Before her death from brain cancer in 1993, Sharon Lund set up a trust fund for her children so that their inheritance would be administered by three trustees. Under the terms of her will, the majority of that fortune was to be paid in three installments on her children’s 35th, 40th and 45th birthdays – with them each getting a 20 per cent share of whatever was in their trust at the time. The rest, according to court testimony, was to be split up into smaller amounts to keep them living in comfortable circumstances and to be given to charities.

But, crucially, these big birthday payouts came with a condition that each sibling be able to demonstrate their “maturity and financial ability to manage such funds in a prudent and responsible manner,” according to a trust document filed as part of the long-running litigation in Los Angeles Superior Court.

The phrase has been seized upon in legal arguments by the twins – both of whom attended schools for children with learning disabilities – and the trustees.

While court records show Brad has received approximately $1 million a year from family trust payouts, he has not received either of his first two big birthday payments, according to a civil suit he filed in Superior Court in 2013 in an unsuccessful bid to end the trustees’ control over his money. He lost that fight, but appealed in August as he continues to try to claim his cash.

Cross-complaints

In addition to charges that neither sibling is competent to handle the vast wealth held in trust for them, Brad has alleged in court filings that the trustees administering the money have been exerting “undue influence” over Michelle to their own financial benefit. The trustees, in turn, succeeded in having the twins’ father, developer William Lund, removed as a trustee as part of a legal settlement.

Neither of the younger Lunds nor their father could be reached for comment.

The trust is now administered by Robert Wilson, a financial manager who according to court documents has been helping the Disney family with their finances for about 40 years, and by two former U.S. Trust bankers: Andrew Gifford and Doug Strode.

Peter Gelblum, a partner at West L.A. law firm Mitchell Silberberg & Knupp representing the trustees, said, “The trustees have the obligation to determine the distributions based on the language of the trust set up by Brad and Michelle’s mother. I can’t tell you what is going to happen next in this case but the fact is that Brad has issued an appeal to the L.A. Superior Court ruling and that will be heard.”

Pending that litigation, the trustees are to decide on whether and how to turn over the third and final birthday lump sums, due in just five months.

Any nondisbursed money can be bequeathed to siblings, children or charity, but with the trustees having full discretion over distributions, according to reports.

Bryan Sullivan, a partner at Mid-Wilshire law firm Early Sullivan Wright Gizer & McRae who has worked on a string of entertainment industry cases, said the Disney family feud could have been avoided with better legal advice at the start.

“If I had a time machine, I would go back and suggest to the mother that she put in some additional criteria to define exactly what ‘maturity and financial ability’ are, because the language of the inheritance criteria is so vague and open to interpretation that it’s going to be fascinating to see how it is ultimately defined in this case,” he said.

“We all know people who are successful but not necessarily financially mature in the way they spend their money,” he added.