ah ha, think we can help you with this
Give each truck in the convoy a name - truck1, truck2 etc
Give your convoy a "Join" waypoint
Give the escort a "Join and lead" waypoint
(or the other way around, whatever)
Synchro these two waypoints. The joint group will follow the subsequant WPs of whoever had Join and lead
Remember that the total number of dudes in a group can't exceed 12, so maybe you could have 6 trucks (=6 drivers) and 2 tanks (each have a crew of 3) 6+3+3=12
Make a big trigger, type End#1. This is going to be your mission complete trigger.
In the condition field of the trigger you are going to put a list of conditions. The condition will depend on exactly what you want to end the mission. Look in the Editor's Depot for the Command Reference Manual and learn about the commands
alive
canmove
Say you wanted the mission to end when none of the trucks could move. Then in the condition field you would have
(not (canmove truck1)) and (not (canmove truck2))
syntax not guaranteed, but you get the picture. When none of the trucks can move the mission will end. Alternatively you could end the mission when all the truck drivers are dead. (If you name a vehicle truck1 then the driver is automatically named truck1D.)
Hope that helps!