I am working on a project that has the following design hierarchy. In a master assembly I have a master construction line sketch part. This master part includes multiple sketch and plane entities, but no solids. I then bring in a part and mate it to a specific plane. The geometry of a part is controlled through an On Edge relations (Convert entities command under sketch tools) to the master sketch in assembly that is located on the aforementioned plane. What I want to do is bring in another instance of the same part, mate it to another plane, and relink the ON Edge relations to the geometry on this new plane. This would become another configuration of the same part.
However I can't find a way to change the geometry to which the relation link is pointing to in a unique configuration. If I change that link in one part it affects all other instances of that part regardless of configuration.
The reason I want to avoid resaving each part as an individual file is because at this stage in the design process the design of the part is unfinished and I would like to make changes and additions to the design without having to repopulate the model with new set of save-as parts.
Any thoughts on how to go about this problem.