Getting Units to "stay" after being told to attack-move somewhere?

I'm using the following action to move a group of Gnolls I've created for Neutral Hostile with another trigger:

Unit Group - Order (my_group) to Attack-Move To (Random point in Gnoll Homeland <gen> )

The Gnolls move as expected, stand around in formation for a few seconds, then get bored and return to their spawn point. I realize this is the normal behaviour for a creep.

Is there any way to make the group of creeps stay and guard the new area, instead of returning to their respective spawn points?

Try the action "AI - Ignore unit guard position". It works on my map. I used it to prevent the ball from going back to the "center mark" of the field. ;)