What I want is a 3D modeling tool that has no distinction between multi-body parts and parts in an assembly.  Basically you make everything as a body and then you build the assembly/feature tree to fit your requirements.  So everything is defined in the context of this global type assembly.  You could establish a BOM at a later time and make up whatever kind of BOM structure you like.  Does anyone know of modelers that behave like this or why this might not be such a good idea?  A high percentage of the problems I have are context related problems but if the context was always global then there would be no problems correct?