Currently the only 2 options are attack everyone in sight or attack hostile in sight, there is no passive or deffensive, and it's general, the same for all.
It's useful to be able to set a general behavior but it would be better if one could set them individually and have:
-Attack all in sight (zombies and any NPC)
-Attack hostiles in sight (zombies and hostile NPC)
-Attack zombies in sight (only zombies, ignore all NPC)
-Deffensive (attack hostiles npc and zeds in a close radius, say 6 tiles arround)
-Passive (wont attack, will run away from any threat)

A general directive would set the group, setting an indiviual would override the previous order.

Survivors - combat stance - Attack all
then...
Doctor Kyle - combat stance - deffensive