Wandering unit group radius

[PFQNiet]

I'm getting started with unit groups, with the main purpose being that groups guard a certain area and, when distracted by the player they go murder and then - on successful completion of that distraction - return to their posts. This all works.

However I would like them to use a "wander" command around their point-of-interest, but this makes them cluster very tightly. Apparently "radius" doesn't apply to unit groups, so that didn't help. Giving each member a separate "wander" command works but appears to dissolve the unit group (as it became invalid when I tried).

Is there a way I'm "supposed" to be doing this?