This happens to me all the time where I have a part or sub-assembly existing in an assembly and I decide to make it a factory file. When I make it back in the original assembly (where it is used) you can see the factory members, but you cannot change to them. Why? You end up having to replace the component with it's self in order to access the newly created factory components. I would like to see it possible so you don't have to go through this painful process.