Claire Boucher, the singer known as Grimes who has three children with Elon Musk, has filed a petition against him in a California court "to establish parental relationship."
The Superior Court of San Francisco says on its website that the "petition to establish parental relationship filed by Boucher, Claire as to respondent Musk, Elon" was entered on Friday, Sept. 29.
Further information about the case is not publicly viewable and it does not appear that Musk has responded to the filing. Samantha Bley DeJean – who has been identified in the filing as Grimes’ attorney – did not immediately respond Tuesday to a request for comment from FOX Business.
The Judicial Branch of California says the petitions to determine parental relationships are used to "get a court order (judgment) that identifies the legal parents of a child.
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"This is used by parents who are not married," its website adds.
Boucher and Musk welcomed a son in May 2020 named X Æ A-Xii, who they call X, and a daughter, Exa Dark Sideræl, who goes by Y, via surrogate in December 2021.
Most recently, it was revealed in a biography of Musk by Walter Isaacson that he fathered a third child with Grimes, named Techno Mechanicus and nicknamed Tau, according to media reports.
The legal proceedings initiated by Boucher come after she recently responded to a tweet by Isaacson showing Musk’s twins with Shivon Zillis, writing, "Tell Shivon to unblock me and tell Elon to let me see my son or plz respond to my lawyer," the New York Post reports.
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"I have never even been allowed to see a photo of these children until this moment, despite the situation utterly ripping my family apart," she reportedly added.
Grimes later deleted the tweet, according to the New York Post, before writing on X in Sept. 10, "I spoke with Shivon at length finally, which was long overdue. This wasn't her fault, plz don't be angry at her! We respect each other a lot and we're excited to become friends and have the kids grow up together."
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"I wish I could show u how cute little Techno is but my priority rn is keeping my babies out of the public eye, Plz respect that at this time," she added.
Attorneys for Musk did not respond to a request for comment.
FOX Business’ Rebecca Rosenberg and The Associated Press contributed to this report.