Put a slider on the cooperative order, which sets the strength of the effect.
Range would be -100 to 100. This would have an effect on the weighting of this factor on target selection.
100 should weight it so strongly that a ship should almost invariably target a ship that is already under fire, if one is in range.
-100 should weight it so strongly to the negative that a ship should almost invariably target a ship that is NOT already under fire, if such a ship is in range (very useful order for specialist ships such as EMP frigates.)
0 should mean that the ship pays absolutely no attention to whether or not a potential target is under fire (useful for specialist ships such as armour breakers, that want to spread their fire fairly randomly through the enemy.)
If the cooperative order has influence from turret to turret, the negative order would be fantastic for things such as dedicated target painter cruisers - since it’d result in the 6+ painters on the ship all targeting seperate hostiles.