problem in MMF2

Right, so I'm working on something, and I have a problem.
I want two objects to destroy each other when they collide but NOT if they are in collision with this other object.
I Know how to make the collision between the two object's condition, but I cannot make a condition for "if avoiding/not collided with _____"... so that's were I get stuck.

any help?

Put the "if overlapping __" condition down with the objects in question. Then right click on the event and click Negate. This in effect says "if it isn't overlapping the object".