Neve Lafferty, 15, and Georgia Rowe, 14, apparently leapt more than 100ft from the Erskine Bridge, in Renfrewshire, in October last year.
They were reportedly holding hands as they plunged into the River Clyde.
At the time they were residents of the Good Shepherd Centre in Renfrewshire.
The unit cares for young girls referred to it by educational and psychological services, social work departments and children's hearings.
A preliminary hearing is due to be held on 20 December at Paisley Sheriff Court and a date for the inquiry will be set once the sheriff is satisfied that all parties are prepared. A Crown Office spokesman said: "We will keep the families advised of the status of the case and any future developments."
Staff at the Good Shepherd Centre said the girls had been on "apparently happy and productive" weekend outings with relatives and were seen going to their rooms before being found to be missing.
A search of the campus was then launched.