The Duke of Sussex has been called upon to give evidence in the defamation case brought by Samantha Markle against his wife, Meghan.
Miss Markle has formally requested that the Duke give a videoed deposition, under oath, later this month.
She has also asked the Duchess of Sussex, her half-sister, to make 38 separate admissions in the case - ranging from the fact that Miss Markle regularly drove her to school and took her on shopping trips to the local mall, to a declaration that neither Queen Elizabeth II nor the King were racist.
Miss Markle, elder daughter of Thomas Markle, the Duchess's father, is seeking $75,000 (£57,000) in damages over claims made by the Sussexes' in their March 2021 interview with Oprah Winfrey and in the 2020 biography Finding Freedom, which she claimed subjected her to "humiliation, shame and hatred on a worldwide scale".
She has accused Meghan of telling "false and malicious lies" about her fairytale "rags-to royalty" upbringing at her family's expense and has contested her half-sister's claim that she "grew up as an only child".
Legal documents made public by the Florida district court last week reveal that Miss Markle wants the Duchess to give a deposition the day before her husband.
Mr Markle has also been called upon to provide a statement, as has Jason Knauf, the Sussexes' former communications secretary; Ashleigh Hale, Miss Markle's daughter; and Christopher Bouzy, who runs an internet security company.
However, the Duchess's California-based legal team has so far declined to provide any information, branding the various requests "irrelevant", "vague" and "speculative".
Her lawyer, Michael Kump, said the proposed deponents had "no discernible connection" to the statements at issue in the original complaint.
He has applied for the case to be dismissed, arguing that most of the statements at issue are not actionable given that Meghan did not make them, and that those she did make were simply opinions, which were "substantially true in any event."
He has also applied for the discovery process to be delayed, pending the outcome of the dismissal application.