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The niece of Lori Vallow, the Idaho mother arrested in connection to the disappearance of her son and daughter, denies knowing where the missing children are.

Attorneys for the niece, Melani Boudreaux Pawlowski, said in a press release that she "strenuously denies" allegations she knows the whereabouts of Vallow's son, Joshua, 7, and her daughter, Tylee Ryan, 17. The children were last seen in September.

Pawlowski's denial comes after her ex-husband, Brandon Boudreaux, alleged in court documents that she knew where the children were.

Boudreaux made the claims in a petition filed in an Arizona court as he and Pawlowski fight over the custody of their four children. He said he has "serious concerns" about his children being placed in the care of his ex-wife because Pawlowski has "knowledge of the whereabouts of her aunt's two missing children" and is refusing to cooperate with authorities as they search for Joshua and Tylee.

Lori Vallow and Chad Daybell. Freemont County Sheriff's office

One of Pawlowski's attorneys, Robert Jarvis, said she has talked to the FBI on three separate occasions and told them that she does not know where Vallow's children are.

In Boudreaux's petition, he also alleged that his ex-wife is "heavily" involved in a doomsday cult. Similar claims have been made against Vallow, whose husband, Chad Daybell, is a self-published author who has written more than two dozen books about near-death and doomsday events.

Jarvis denied Pawlowski is involved in a cult, stating in the press release that she is a member of The Church of Jesus Christ of Latter-Day Saints and believes "in a loving God."

Garrett Smith, another of Pawlowski's attorneys, said Boudreaux lied in his court documents in retaliation against his ex-wife and is simply trying to get full custody of their children, who range in age between 2 and 10 years old.

The attorneys allege that Boudreaux, who has temporary legal custody, took the children out of Arizona. Pawlowski and Boudreaux had a child custody hearing on Thursday but Boudreaux did not show up, according to her attorneys.

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Smith told NBC News in a phone interview Friday that Pawlowski and her legal team believe her children are in Utah, where Boudreaux has family. He said it's been several months since Pawlowski has seen her children.

“Everyone is asking, ‘Where are Lori Vallow’s children?’ Why is no one asking the same question about Melani’s children?” Jarvis stated in the press release issued Wednesday.

An attorney for Boudreaux did not immediately return NBC News' request for comment.

Pawlowski and Boudreaux's custody battle is the latest in a string of twists and turns related to the Vallow case.

Police in Rexburg, Idaho, began searching for Vallow's two children in November after they tried to conduct a welfare check on Joshua.

Authorities said that Vallow and Daybell were not cooperating with the investigation and had left the state. The couple was later found in Hawaii, and Vallow was arrested and charged with desertion and nonsupport of dependent children.

She is being held in Hawaii on $5 million bail, awaiting extradition back to Idaho.

According to Rexburg police, the disappearance of Joshua and Tylee could be connected to the death investigation of Daybell's first wife, Tammy Daybell. The 49-year-old's death was initially ruled as natural after she was found dead in her home, but has since been classified as suspicious, police said.

Joshua Vallow and Tylee Ryan. Freemont County Sheriff's Office

Authorities in Arizona have also said they are investigating the death of Vallow's former husband, Charles Vallow. He was shot and killed in July 2019 by Lori Vallow's brother, Alex Cox, following a confrontation.

One of Charles Vallow's sons told the East Idaho News that he and his two siblings found out about their father's death via text messages from Lori Vallow.

In the text messages, obtained by the local news outlet, Lori Vallow tells Charles Vallow's sons that she has some "very sad news."

"Your dad passed away yesterday. I'm working on making arrangements and I'll keep you informed with what's going on. I'm still not sure how to handle things," it reads. "Just want you to know that I love you and so did your dad!!"

The message thread shows that several of the children's attempts to gather more information on their father's death went unanswered.

"You can't just tell us [our] dad died and disappear," one message to Lori Vallow reads. "You're not too busy to just let us know he died and disappear."

Another reads: "Okay Lori. It's been 3 days. You let us know our father passed away over a text message. 3 days and we haven't heard from anyone. ... We need any information you have."

The son, who did want to be identified, told East Idaho News that Lori Vallow never gave them details on their father's funeral. The children eventually found the mortuary where Charles Vallow's body was and held their own memorial service, which the son said Lori Vallow did not attend.

Lori Vallow and Cox were questioned by police over Charles Vallow's death but have not been charged. The Associated Press reported that Cox died in December.