use System: For Each (object name) on your events.
and you could identify which enemy is partnered with which enemy box (or vice versa) by using this method:
pin the enemy to the enemybox, then you can use the condition "Pick by evaluation"
For example:
+EnemyBox: Life > 0
+For Each EnemyBox
-> your actions
-(Sub event) Pick Enemy where EnemyBoxUID = Enemy.pin.pinnedUID
-> your actions
Pick Enemy where EnemyBoxUID = Enemy.pin.pinnedUID
means that you pick the enemy object that is pinned to the specific instance of the enemybox object
you can use it the other way
Pick EnemyBox where EnemyBoxUID = Enemy.pin.pinnedUID
means that you pick the enemybox object that you pinned the specific instance of the enemy object to
Read more about both concepts first on the manual to understand it better before attempting to use it.
as for reacting independently, you have to use random to randomize the AI. of course use "For Each" in the events.
reply with my name if you need a capx sample.