Currently, you can form a sub-weldment in a part, but you can't re-use that sub-weldment in another part.  You can only save it out to document separately.

We should be able to bring that sub-weldment into other parts to be re-used along with it's properties, treating them in the exact same way we treat sub-assemblies.

1. You can re-use them in higher level assemblies

2. You can open them individually to document their members in teh cut-list

3. If you have (for ex.) 2 instances of a sub-weldment, they could be grouped in the BOM together with quanitity 2.  Quanity values currently for sub-weldment are completely non-sensical in current SolidWorks.