The boss of the Modell’s Sporting Goods empire is fighting a bid by his sister-in-law to appoint a money manager who once convinced her to invest with Ponzi villain Bernie Madoff, The Post has learned.

Company CEO Mitchell Modell says he doesn’t trust financial adviser Bert Brodsky with a $55 million trust his brother, Michael, left to widow Abby and their three children, according to court papers.

The fund had three trustees, Mitchell, Abby and, until recently, longtime family friend Joel Rosenberg, who died earlier this year.

Among Mitchell’s complaints are that Brodsky once asked Abby for a $2.5 million loan, that he wanted a spot on the sporting goods company’s board, and that he is “hostile” toward Mitchell.

Mitchell says Brodsky got Abby to park some of her dough with Bernie Madoff, who ripped off investors with a multibillion-dollar Ponzi scheme. Abby sought compensation from a Madoff victims fund.

“Bert Brodsky is not an appropriate successor trustee in that he is self-serving,” Mitchell says in a recent Manhattan Surrogate’s Court filing.

Abby counters that Brodsky is a successful businessman with skills that “equip him to act in the best interest of Abby and her children,” Abby says in court papers. He will waive all trustee commissions, she says.

Her three children also support Brodsky. “Mr. Brodsky and my father were close friends and professional associates,” son Andrew Ryan Modell said in a supporting affidavit.

Brodsky told The Post: “Overall, my advice has been very successful.” He also said the $2.5 million loan request was withdrawn when he realized it would be a conflict of interest, and he denied he has anything against Mitchell.

“I’m not so much adversarial to Mitchell as pro Abby,” he said.

A judge will determine if Brodsky gets the gig.

The in-laws have also fought over expense accounts, with Abby claiming Mitchell billed the company for a $116,000 steak dinner while Mitchell said Abby charged $200,000 for gym memberships.

Michael died in 2001 at age 48 of Hodgkin’s disease.