AI aircraft make intersection departure

I managed to programme my General Aviation AI aircraft to make an intersection departure (not use the full length of the runway, but takeoff halfway down) using AFCAD to make a duplicate of the airport with the runway and taxiway shorter. But the tower then gave me clearance to takeoff using the full length while an AI aircraft further down was also taking off.Does anyone know a better way of doing this so you don't get two aircraft taking off at the same time on the same runway?