Say u got 2 M113's and 12 soldiers do this....
Name the M113's m1 and m2
In the init field of each soldier put
this moveincargo m113name
Where m113name is either m1 or m2
then put a waypoint for each m113 to the place u want to go
and an "Unload" waypoint for each m113
and a "Get Out" waypoint for the groupleader synced with one of the m113 "Unload" waypoints
try that, it might work. ;D