Or to rephrase: There are friendly troops on the map but I am not commanding them.
A: How to get them to retreat when the enemy fires a trigger OR;
B: How to get troops to move to another position when the enemy fires a trigger?
(Is my understanding correct?)
Give the troops a move waypoint to waypoint 1. This might be just 5 meters or so.
Give the troops a move waypoint to waypoint 2. This represents their withdrawl and I presume would be somewhere to the rear.
Use "Synch" to synch waypoint 1 with the trigger.
When the mission starts the soldiers will move forward 5 meters and stop. When the trigger is fired they will move to the second waypoint.
I suggest that when they arrive at the second waypoint that their arrival fires a second trigger. This trigger would include the command that all the men face a given direction ie face the enemy advance. Otherwise they will have their backs to the enemy!