I seem to be having some serious workflow problems with Unity. My objects are breaking their prefabs whenever I add physics and scripts to them, and they refuse to convert back into a prefab afterwards. This means that my levels are currently not using any prefabs, and in general they're pretty messy to work with. when I change anything I have to rebuild it all. Also, this breaking prohibits me from editing their original models in MAX and re-exporting. Is there any recommended solution for how to import models and add scripts without breaking the original prefab? Is it possible to assign some of the objects within a model to be colliders and others not to be? The "GameObject -> Upload Changes to Prefab" doesn't seem to work for me most of the time. Is there any documentation to suggest when this does and doesn't work? What does it take to break it?