Changing "defend range" for computers?

[StangtennisGuru]

So Acqusition Range usually decides how far away a unit or hero will automatically acquire targets and start attacking them, but this normal range doesn't apply if you attack a unit that is friendly to the target within a certain "defend range" which can be longer than the acqusition range. From testing it seems to be roughly 800 at least for heroes in my map. If a friendly unit within that range is attacked, the Hero will acquire that as a target regardless of how far away it is. It also seems to be unrelated to "Call for Help Range" in gameplay constants.

So my question is simply if there is a way to reduce this defend range or maybe even disable it entirely? Either globally or for specific units.

I know there are various triggers related to "Guard Positions" but don't know if they work/if they're related to this and on top of that they specifically state that they can't affect Heroes, which is exactly what I need to do...