Pte Cheryl James was one of four soldiers who died at the Deepcut barracks between 1995 and 2002 amid claims of bullying and abuse.
Her family's lawyers want the scope of a new inquest into her death widened.
Pte James, 18, from Llangollen, Denbighshire, was found with a bullet wound to her head in November 1995.
Alison Foster, representing Pte James's family, told a pre-inquest hearing at Woking Coroner's Court they had material suggesting she "may have been sexually coerced or raped the night before, or before the time of her death".
She told the hearing: "There is now a direct allegation that Cheryl might have been ordered to sleep with the person we are calling Witness A by someone superior in rank to her.
"This is not fraternising. This is not an illicit sexual relationship between two young people across the ranks. This is something quite different."
A fresh inquest into the death of Pte James is due to start on 1 February and is expected to last seven weeks.
It was ordered after High Court judges quashed an open verdict recorded in December 1995.
Ptes Sean Benton, James Collinson and Geoff Gray also died from gunshot wounds at Deepcut.
A teenage army recruit who was found dead more than 20 years ago may have been sexually exploited by senior ranks, an inquest is told.