Kirsten Heaven, who represents Cpl Ellement's two sisters, told the inquest: "The family are devastated and upset this disclosure has come so late in the day."
Adjourning proceedings until Monday morning, the coroner said there was a "danger" in pursuing information which was "unrealistic to find" and which may be of little relevance to the inquest.
"I suggest all urgency is given to track down any missing documents," Mr Rheinberg said.
"I'm going to grant the application (for adjournment) on strict and immediate terms."
A coroner's ruling into the death in Wiltshire of Anne-Marie Ellement, a soldier who said she had been raped and bullied, has been unexpectedly delayed today.
It comes after lawyers for the military revealed they had uncovered new documents, including a reference to a diary and mobile phones Corporal Ellement's family say were never passed to them.
Lawyers for the family of Royal Military policewoman, who was found hanging at her barracks in Bulford in October 2011, have accused the military police of a gross breach of guidelines on evidence disclosure.