I would think you'd just want an ClickListener for each object. Handle "enabling" the other two objects in the first object's click event, then when those two objects are clicked on, invoke the method to form the relationship. You don't want to wait in the first object's event handler.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.