Kevin Costner struggles in asset battle amid expensive divorce from estranged wife Christine Baumgartner

As Kevin Costner's divorce to Christine Baumgartner shapes up, it appears the star's estranged wife is asking for more than Costner has offered up.

While facing pricey requests from his estranged wife in the courtroom, an unnamed source claimed to People the Yellowstone star, 68, "wants to hold on to as much as he can."

The source's comments come less than two weeks after Baumgartner filed documents to California's Superior Court asking for $248,000 (approx. $375,865) per month in child support.

Despite the couple's prenuptial agreement limiting Baumgartner to a settlement of just $1.4 million (approx. $2,121,910), documents filed on June 16 show that she's requesting more than six times the $38,000 (approx. $57,602) a month Kevin had offered.

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Speaking to Baumgartner's requests in court, the source claimed to the outlet: "She wants Kevin to provide what they are used to" and explained the life the family had become accustomed to included private jet trips and stays in luxurious hotels.

After getting her own lawyers to work out some calculations, Baumgartner's court filing detailed the spending of the family which was well over what the terms of their prenuptial agreement were offering her.

In the court filing, the former handbag designer, 49, alleged the figure "is less than the amount needed to maintain the children in their accustomed lifestyle".

The couple share three kids: Cayden, 16, Hayes, 14, and Grace, 13, and Baumgartner additionally requested that Costner cover the full amount of their children's private-school tuition, extracurricular activities/sports and health-care expenses.

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The publication also reached out to an unconnected family lawyer for comment who believes that child support cannot be specified in prenuptial agreements.

This is because the circumstances of the family and needs of children at the time of a couple's split are hard to predict.

"The bottom line is what is in the children's best interests," family lawyer Randy Kessler, who does not represent either of the parties involved told People. "The court must consider their standard of living while their parents were married."

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This isn't the first contentious point in the A-lister's divorce proceedings.

Costner has previously brought issues concerning the pair's prenuptial agreement before the court.

One allegation being Baumgartner's refusal to move out of the home within the specified 30-day-period, and the other Costner's claims that his estranged wife secretly charged money to his credit card refusal to move out.