Have the bad guys start out as neverfire and stealth. Then have a script runing that monitors the M113. When the M113 dies make all the bad guys go into fire at will, combat mode. I am at work, and I do not know the command syntax to do this of the top of my head, but I will give you a script example when I get home. I've already done something similar, so I will just paste that as an example.