Theres probably a simple solution but i just dont know what it is.

Example. Im playing WoW in AV. Toon 1 and 2 both casting a spell to the target. Target freaks and runs toward me behind Toon 2. Toon 1 which is me turns around with the mouse and continues to attack while Toon 2 isnt within Line Of Sight. How do i make Toon 2 automatically turn to where ever his target is?

PLEASE HELP! Thnx!