Grimes has taken legal action against Elon Musk over parental rights of their three children.
On 29 September, the Canadian musician filed a petition in Los Angeles to "establish a parental relationship", Page Six reported on Tuesday.
The filing follows weeks after it was revealed that Grimes, 35, and the former chairman of Tesla, 52, share a third child.
The request intends to have the court identify the legal parents of a child when they are unmarried. The petition has not yet outlined whether Grimes, real name Claire Boucher, is seeking custody rights or child support.
According to the Page Six, the filings are sealed, though it does appear that Musk has not yet responded to the petition.
The pair first began dating in 2018. After three years of an on-and-off relationship, they broke up for good in 2021.
Grimes and Musk welcomed their first child, a son named X Æ A-Xii, in May 2020. They then welcomed their daughter, Exa Dark Sideræl, aka Y, in December 2021.
In September, it was revealed in journalist Walter Isaacson's Elon Musk biography that Grimes had given birth to a third child, Techno Mechanicus, also known as Tau.
Soon after the news of Tau's birth broke, the Genesis singer took to X, formerly known as Twitter, to ask Musk to let her see her son after Isaacson shared an image of Musk's twins, whom he shares with Shivon Zilis.
"Tell Shivon to unblock me and tell Elon to let me see my son or plz respond to my lawyer," she wrote in a since-deleted post. "I have never even been allowed to see a photo of these children until this moment, despite the situation utterly ripping my family apart."
Musk has been married three times, and according to reports, is the father of at least 11 children.
