Attorneys representing victims of former sports doctor Larry Nassar have been given until the end of February to modify their federal lawsuits, which includes adding more names to the burgeoning list of plaintiffs.

More than a dozen lawsuits have been filed in California and Michigan, including several in federal court in Grand Rapids.

The lawsuits arise out of multiple incidents of alleged sexual assault, battery and harassment of girls and women by Nassar, who worked at Michigan State University and was a longtime doctor for USA Gymnastics.

MSU and USA Gymnastics are high profile defendants in the lawsuits. They’ve filed motions asking that the cases be dismissed.

MSU attorneys concede that Nassar is a “pedophile and a criminal,’’ but says the university is not legally liable for his sexual assaults on patients. USA Gymnastics says the statute of limitations has expired in most cases. Its legal team also says Nassar – and not USAG – is liable.

Attorney Stephen Drew, whose Grand Rapids law firm is representing dozens of clients, says he and other lawyers plan to “vigorously oppose’’ motions for dismissal.

“Our clients want change; they want this to never happen again,’’ Drew said on Friday.

About 150 plaintiffs are currently suing MSU, USA Gymnastics, Nassar and others. Drew said he expects that number to approach 200 by the end of February.

Okemos attorney David Mittleman agrees. His law firm anticipates adding more clients before the court-ordered deadline of Feb. 28.

“We are going to be adding additional plaintiffs and we intend to raise serious fraudulent concealment issues, primarily against MSU,’’ Mittleman said.

The fraudulent concealment issues, he said, fall under the Racketeer Influenced and Corruption Organizations Act, commonly known as the RICO Act. The federal statute allows private parties to bring civil claims for violations.

“All I’m trying to do is shine the light and tell the truth,’’ Mittleman said. “Individually, they have not been listened to for over two decades. Collectively, they are starting to be heard.’’

The lawsuits seek unspecified monetary damages for the victims, who ranged in age from nine to 29 at the time of the alleged abuse. They participated in a wide range of sports, including gymnastics, softball, basketball, soccer, figure skating and swimming.

According to the complaint filed by Drew’s firm, Nassar treated hip, leg, back and ankle injuries with his ‘‘inter-vaginal adjustments.’’

Nasser, 54, was sentenced this week to between 40 and 175 years in prison for assaults that occurred in the Lansing area. A federal judge in December sentenced him to 60 years in a child pornography case. And he’ll be sentenced next week in Eaton County on three counts of first-degree criminal sexual conduct, a potential life offense.

Drew contends Nassar could have been stopped if allegations of abuse were taken seriously when they first surfaced some 20 years ago.

Among his clients is Rachael Denhollander, 33, a former Olympic gymnast who was the first to come forward publicly and say Nassar molested her as a child.

“When a child comes to you or a young woman comes to you and says he’s doing these things, the first thing to do is to stop and listen,’’ Drew said. “You’ve got to put the person and the athlete ahead of the prestige of the program. You just do. They are your program.’’

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