Maybe the solution to this is to support part kits.
I know about the solution of using the part inventory location to create a hierarchy, but as you can see, having a parent id hierachy would be very useful in such cases and well as in order cases (e.g., having a parent Electrical type or category which included various collections of inter-related parts (e.g., EMT connectors, Liquid-tight connectors, Water-tight connectors, etc. Most inventory systems use a custom numbering system based on hierarchies, allowing one to associate individual parts with parent subassemblies, and subassemblies with assemblies and assemblies with parent equipment.