Kevin Costner's estranged wife, Christine Baumgartner, has requested that the court force the star to produce "all statements, receipts, invoices, canceled checks (front and back) and other documents ... relating to any extramarital romantic relationships" as part of her quest to dig into the actor's finances amid their contentious divorce battle.

In legal documents filed Monday in Santa Barbara County Superior Court and obtained by ET, Baumgartner, 49, attached exhibits showing her list of demands and, among them, financial documents reflecting expenses paid for by Costner, "or any person at your request or on your behalf, relating to any extramarital romantic relationships." She's requesting that the court now force Costner to produce these documents.

Regarding this request, Costner, 68, has maintained he "has no responsive documents for 'extramarital romantic relationships' in which he engaged because he engaged in none." Furthermore, Costner has also asserted he "does not know for a fact if [Baumgartner] engaged in any 'extramarital romantic relationships" before separation and, if so, whether she spent any of his money or charged any expenses in furtherance of her affair(s) on credit cards he paid."

The "extramarital romantic relationships" mention -- made in her demand for production of documents, which were attached as exhibits in her recent 112-page court filing -- is interesting, considering a former tenant of Costner's denied back in June of having an inappropriate relationship with Baumgartner.

In the court documents she filed Monday, Baumgartner requested that the court compel the Yellowstone star to hand over bank and credit card statements as well as contracts highlighting "anticipated income." She also accused Costner of being "evasive" about his finances and that whatever documents he has turned over have, so far, been "deficient."

She claims he has "failed to produce a myriad of bank account and credit card statements which are directly relevant" to the contested child support matter. As previously reported by ET, Baumgartner initially requested $248,000 per month in child support, while Costner said he could pay $51,900. Ultimately, the judge in the case ordered Costner to pay her $129,755 per month until the matter can be settled at an upcoming hearing, set for Aug. 31 and Sept. 1.

Until then, Baumgartner has been trying to dig into Costner's finances, and she says she's "entitled to conduct discovery regarding [Costner's] financial circumstances" and he is "not entitled to ignore those reasonable requests and withhold the relevant documents" she's been requesting.

For example, Baumgartner says Costner has asserted he anticipates his income will decline, as he is no longer involved with the hit Paramount TV show, Yellowstone. But as far as upcoming projects -- specifically Costner's Western, Horizon, in which he's starring and directing -- Baumgartner claims Costner's been "withholding documents" that outline "anticipated income."

In her filing, Baumgartner claims Costner's team objected to producing those documents because they are "highly confidential," which Baumgartner referred to as a "smokescreen." Furthermore, Baumgartner says Costner's actions clearly rise to the level of "stonewalling and evasion" of the discovery process.

Baumgartner not only wants the court to compel Costner to hand over the financial documents she's requested, but to also sanction the actor to the tune of $8,985 -- the amount she's incurred in attorney's fees and costs in order to file her request in court.

For his part, Costner claims his estranged wife's requests for such documents are "burdensome, oppressive and harassing."

This is the latest development in the former couple's messy divorce. Earlier this month, Costner accused Baumgartner of using "stalling tactics," after she claimed that she did not understand their prenup agreement when she signed it.

In an early July filing, Costner claimed that the prenup she signed when they tied the knot in 2014 stipulated that Baumgartner agreed -- in the event of a divorce -- the actor would have exclusive possession and use of his separate property residences, and that she would vacate any separate property family residence she was living in within 30 days of the filing of a divorce petition.

In her response, Baumgartner stated she would not move out of the property unless Costner agreed to her child support request. At the time, Baumgartner -- who shares sons Cayden, 16, and Hayes, 14, and daughter Grace, 13, with the actor -- was ordered to vacate the home by July 31. She has since moved out of the Santa Barbara estate, but not without a fight.