Triggering units to target multiple units without them all heading to ONE unit

How do you trigger a spawn of units to attack multiple units instead of One unit without there being an order of who they kill first and then second etc. Is this possible if so please tell me how.

Attack Move.

Real Answer: Sub Target Modifer: Attack Target Location = Unit Area + Range + Collision --> Targeted Unit (Autogen AI Implement) :: Set Per Mile Field = Dial To Unit Collision Attack Size/Class - Unit SelfTaunt 6gRng

This is usally works for any game, it allows a computer AI to target Heroes and or Specific units.
For the reverse effect instead of them targeting a Building over units, you just use a Sub Target Modifier for Unchecked Defensive Structures, and Heroes. And it will no longer attack those targets when using Attack move or ("A" + Click Area)

Thank you, now i may get the map done after some more complications are fixed.

ummm not to sound like a complete noob but how do you get the sub target modifier?