no.
You don't have to have a scrum half even in normal circumstances. The 9 may either stand in the usual place, or 5m back with the other players.
[LAWS]20.12 Offside at the scrum
(a)
When the scrum is set, the scrum half not throwing the ball into the scrum must take up a position either at the same side of the scrum as the scrum half throwing in the ball or behind the offside line defined for other players[/LAWS]