Witness accounts are being sought from Virginia Giuffre’s partner Robert Giuffre and Dr Judith Lightfoot, according to court documents.
Both Mr Giuffre and Dr Lightfoot are residents of Australia and would be requested to be examined under oath, either in person or by video-link.
The legal requests come after the news earlier this week that a judge had thrown out a motion by Andrew’s lawyers to dismiss the case, ruling it can go to trial.
In recently published documents, lawyers for the Queen’s son argue that Ms Giuffre “may suffer from false memories”, and state that Dr Lightfoot should be examined on “theory of false memories” among other topics including matters discussed during their sessions and any prescriptions she wrote for Andrew’s accuser.
They also wish to be allowed to inspect documents including the doctor’s notes from all sessions with Ms Giuffre.
Meanwhile, the lawyers want Mr Giuffre to be questioned on a range of areas including the circumstances under which he met his now wife around 2002 and the Giuffre household finances.
Lawyers want testimony to be obtained from the witnesses by April 29 this year “or as soon thereafter as is possible”.
The trial is scheduled to take place between September and December.
Andrew’s lawyers have requested that the US court issues letters to the Central Authority of Australia for their assistance in obtaining the testimony.
The requests from the duke’s lawyers follow similar requests from Ms Giuffre’s legal representatives.
Her team is seeking witness accounts from Andrew’s former equerry Robert Olney and a woman called Shukri Walker, who claims to have seen the royal in Tramp nightclub.
Documents submitted by Ms Giuffre’s legal team say that Mr Olney’s name appears in Jeffrey Epstein’s phone book under “Duke of York”.
They say this means it is likely Mr Olney has relevant information about Andrew’s travel to and from Epstein’s properties during the relevant period.
The documents say Ms Walker has stated publicly in the press that she was a witness to Andrew’s presence at Tramp during the relevant time period with a young woman who may have been Ms Giuffre.
Ms Giuffre is suing the duke in the US for allegedly sexually assaulting her when she was a teenager and claims she was trafficked by Andrew’s friend, convicted sex offender Epstein, to have sex with the duke when she was 17 and a minor under US law.
The duke has strenuously denied the allegations.
The duke is also alleged to have abused Ms Giuffre on another occasion during a visit to Epstein’s private island, Little St James, and on a separate occasion at Epstein’s Manhattan mansion.
The fallout from Andrew’s civil sex case continued on Friday as he faced calls to pay for his own security and lose his dukedom.
Criticism of Andrew is mounting after the Queen stripped him of his remaining patronages and honorary military roles as the monarchy distanced itself from the duke ahead of potentially damaging developments in his lawsuit.