Make ally units dont abandon X area

[sebalarios]

You see. I have a ally group that you supposed to support in my custom map. The problem is that every time that a enemy wave comes to attack they go to face it, and when they kill everyone, including the casters that are way far away they dont return to his original positions and they are caught disperse in the next wave and get killed one by one. I want them to defend but not go so far of his original positions.
I would appreciate any help=).

 

[Cheshire]

trigger them to patrol the area you want. that should make them fight in the area, but also return to their patrol route when enemies are dead.