I created a mission where 4 Abrams tanks were traveling in trail formation and a group of Soviet vehicles were placed individually in a spread formation traveling at the Abrams. Both were given whatever command it was to attack any enemy along the way. I entered the mission got to a safe altitude and hit autopilot at about 300 kts and then hit F12. F12 puts you outside the AC and allows you free rein to look around the world using the look around hat switch and the + and - key on the keypad.
What I did was focus on the armor battle. BMP's with anti-armor missiles always fired first as they our range even the Abrams. Also a big factor in who fired first was the terrain. If the terrain is roling, they might not see each other, which happened a few times. Indeed once the formation is stopped, for a few minutes the formation stayed intact and the only person who did fire was the lead tank until he was destroyed. After a few minutes the other tanks went around but it took awhile. I changed formation for the next test and they all fired on the on-coming hoard.
I then individually placed the Abrams in a defensive posture instead of putting a group of 4. I then had the Soviets attack again and man oh man what a battle. Seems that the logic in the first tests were slow to switch to the other tanks in the trail formation. Placing them individually gives them free rein. If you want a group in trail formation you can still do it individually because they all travel the same speed. You would just have to use the waypoints liberally. Trail formation of one group of vehicles places them too close together, realistically, anyways. Takes more time to place individually but the results are far more realistic.