Are there any rules about firing at a target that is in combat with another PC in an adjacent hex to the target? And further, firing at foes that are grappling or for any other reason, in the same hex? I didn't see anything, and a lazy Sunday morning search in the LAW forum didn't turn anything up.
It just doesn't seem right to allow firing at an opponent fighting next your friend w/o considering friendly fire side effects. Maybe something like: 4/DX check to hit the desired foe? If you miss that, then you must roll 3/DX check, and that success causes you to hit your friendly target (or one of them randomly if there are >1 adjacent to the foe target). Something like that. Something to discourage an archer just sitting at the corner of the room and firing at foes w/o any friendly fire side effects.