Create several opfor units and sync them to the hide and show module. Use a trigger to activate the opfor, for example... when blufor enters the trigger the opfor will appear and now the AI and the enemy will fight.
Once everything is created test it with a normal squad, don't switch to team mates, the AI and enemy will behave perfectly. Restart and test it while in a vehicle, step out the vehicle and activate the hide and show trigger, you will see that the enemy will still fire back BUT! Your squad AI won't.
Restart and now try it again but instead switch to each unit in your squad, activate the hide and show trigger and now your squad will not fire back, but the enemy will.