Other signals should be covered if there is the slightest chance of needing them. Also, the movement of the lead's aircraft can convey signals. The signal to move out to route position is yaw the aircraft with rudder for two cycles. To direct wing to the slot or trail position, we used a small porpoising of the aircraft. Make others up if desired, but remember not to make them too drastic.
Paybacks can be rather startling.
Of course, no one wants to admit that he doesn't understand, but that surely beats the alternative, sometimes. More accidents and fatalities stem from these problems than you would think. Other than aerobatics, the most dangerous phase of formation flying is the join-up. Getting into position quickly seems to be the unwritten law, but is not always the best approach. If it doesn't, you will eventually hit him right where you are looking.