Musk and Zilis filed a petition in a Travis County, Texas, court in April to change the twins' names to
"have their father's last name and contain their mother's last name as part of their middle name,
a request a judge approved in May, according to Insider,
which published a copy of the court petition but redacted the twins’ names.
The twins were reportedly born just weeks before Musk and his former partner Claire Boucher
better known by the stage name Grimes, had a second child through a surrogate last year.
Zilis, 36, has worked in top roles in several Musk ventures,
serving as a board member of OpenAI starting in 2020 and project director at Tesla from May 2017 to August 2019.
Musk and Zilis did not immediately respond to requests for comment from Forbes.
Musk rarely shares photos of his children, but he tweeted a picture Friday of him and four of his sons meeting Pope Francis.