Welcome, Foxfaye! <img src="/ubbthreads/images/graemlins/smile.gif" alt="" /> (Yay! Another Australian! <img src="/ubbthreads/images/graemlins/delight.gif" alt="" /> )
If you right click a character portrait, you can set them to Agressive mode. So long as that character isn't the leader (the leader has a gold box around their portrait), they will automatically attack all foes in sight. Though I found it necessary to give weaker characters a ranged weapon for this as too much melee can be bad for one's health.
It's not quite what you're asking for, but it's something. If your characters are near each other, the Agressive one will draw foes away from the leader.
