Deborah Simon, who’s seeking to remove her stepmother from overseeing a trust that holds her late father Melvin’s fortune, is asking a court to pass over the two Indianapolis businessmen who normally would be next in line for the job.

Language in the trust stipulates that if the stepmother, Bren Simon, is unable to serve as trustee because of incapacitation, resignation or death, Deborah’s brother, David, Simon Property Group’s chairman and CEO, would step into the role. And if he couldn’t serve, retired Katz Sapper & Miller partner Bruce Jacobson would become trustee.

But in a filing Monday seeking Bren’s ouster, Deborah instead favors appointment of a disinterested corporate trustee. The filing, first reported by IBJ, says that neither David Simon nor Jacobson should fill the role because both will be witnesses in the lawsuit she filed Jan. 7 contesting changes in the will that Melvin executed in February 2009—seven months before he died at age 82.

The changes boosted the portion of Melvin’s estate going directly to Bren, 66, from one-third to one-half. They also wiped out the portion that was to go to Deborah, David and their sister, Cynthia Simon-Skjodt.

Deborah contends Melvin was suffering from dementia and even needed help signing his name. Bren asserts the changes reflected Melvin’s wishes and he understood what he was doing. It acknowledges he needed help with his signature but attributed that to "Parkinsonian symptoms" affecting his right hand.

Jacobson, a longtime financial adviser to Melvin and Bren, witnessed the changes and “held and moved Melvin’s hand as he allegedly signed the altered will and trust,” according to Deborah’s lawsuit.

Deborah’s effort to oust Bren is the latest twist in an escalating battle over an estate that could be worth $2 billion.

In Monday’s filing, Deborah said it’s inappropriate for Bren to remain as trustee of The Melvin Simon Family Enterprises Trust while her lawsuit challenging the changes plays out. She argued appointment of a corporate trustee would “ensure that the assets of the trust and the interests of all beneficiaries are adequately protected.”

That step also is necessary, the filing asserts, because of “the level of distrust and animosity that exists between Bren Simon” and Deborah, David and Cynthia.

Furthermore, the filing says Bren’s recent efforts to convert part of Melvin’s ownership stake in the mall giant into common shares or cash cast doubt on her ability to properly carry out her duties as trustee.

Bren Simon notified Simon Property Group on Jan. 12 that she was electing to convert 6.5 million so-called partnership units held by her late husband into common shares or cash, at the company's discretion. The units are worth about $480 million based on recent trading in the company's shares.

The company responded that it could not convert the partnership units because of Deborah’s legal challenge. The company filed suit against Bren last week asking a judge to settle the dispute.

Deborah’s filing Monday suggests Bren’s behavior was reckless.

“Even if the trustee wanted to diversify the trust’s assets, the decision to potentially divest more than 6.5 million shares of stock in one day—at whatever average price the stock happened to be trading at for the previous five days—cannot conceivably be viewed as consistent with the duties of a prudent fiduciary to preserve the value of the trust’s assets for all beneficiaries,’’ the filing said.

“Any sensible investment adviser seeking to diversify assets would do so in a prudent, planned manner over a significant period of time.”

An attorney for Bren Simon could not be reached for comment.