1) Place a Marshall with all three crew selected as playable
2) Control the commander. Confirm that you can enter optics mode and change the variable zoom level
3) Use mouse wheel action menu to move to driver seat
4) Use team switch to take control of the crew member who has now been moved to commander seat (but is not the actual squad leader of the group and was previously the driver)
5) Confirm that you can still enter optics mode but that you can no longer change the variable zoom level.