Kevin Federline has accused Britney Spears' father, Jamie, of physically abusing his 13-year-old son, Sean Preston.
The rapper's representative, powerhouse Los Angeles family law attorney Mark Vincent Kaplan, tells PEOPLE that the alleged incident occurred on the evening of Aug. 24 while Sean Preston and his brother, Jayden James, 12, were on visitation with their mother at Jamie's house.
A representative and lawyer for Spears did not immediately respond to PEOPLE's requests for comment. Jamie was also unable to be reached by PEOPLE.
"There was a disagreement that occurred while Britney and the children were visiting with Jamie at his home that led to a physical altercation that was observed by Jayden," Kaplan says. "Britney did the right thing and removed the children and took them out of there, but the trauma to the kids is nonetheless."
The Blast reports that Jamie allegedly "violently shook" Sean after breaking down a bedroom door to reach him.
As a result, Kaplan says he and Federline, 41, went to the Ventura County Sheriff's station the next day, Aug. 25, to file a police report in an attempt to obtain an emergency protective order for his kids. Kaplan says that they decided not to proceed with an "evidentiary hearing on the domestic violence order against Jamie" after notifying Britney's lawyers and attempting to work things out.
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Additionally, the alleged incident prompted Federline and Kaplan to file documents on Aug. 28 to officially adjust the former couple's previous 50/50 custody agreement. Now, Kaplan says Federline has custody of the boys for "closer to 90" percent of the time, while Britney, 37, has them for 10 percent of the time - an arrangement which Kaplan says has been unofficially in place for "almost the last year."
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Though several outlets have reported that the new custody agreement grants Britney unsupervised visitation rights, Kaplan claims "that's not the way this is."
"The custody remains supervised," he says.
Regardless of what might have happened with Jamie, Kaplan says Federline and the boys are both "doing great" now.
"It was important to Kevin that regardless of this event that the kids still had continuing and meaningful contact with their mother," he says.
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Earlier this month, Spears shared a rare photo of her two sons during a weekend trip to Disneyland.
"Great time at Disneyland today … but I don't remember ever getting that wet on splash mountain ????!!!" Britney captioned her Instagram post. "Geeez … anyhow my boys are older now, so they don't like their picture taken ever … so I was thrilled today when they said SURE !!!!! Such a great place !!!!!"
A source close to Spears recently told PEOPLE that Britney is doing better after a rough start to 2019, which included time spent in a wellness treatment facility as she also dealt with Jamie's health battle following a colon rupture.