Turret not targeting a specific instance

Hello all,

I have turrets that can be placed by the player in game. From created they target a family named "enemies" which includes several different sprites. Occasionally one instance from a sprite in this family will enter a state where it is immune from being targeted by turrets. How can I make it so that turrets don't target that instance while still attacking other instances of that sprite. I don't really have a capx to post because I haven't the foggiest idea of how to do that. Any ideas?

Thanks

Create a family instance variable and toggle this to a different value for the family instance when the instance is picked as immune. Then under the acquiring target events add a condition that the family instance must have family instance variable set to the non-immune value to be picked.