William, What we practice here at our company is that we import the vendor's model (part or assembly) as a pro/e part. Many neutral formal assembly files can be imported as parts. That way, it will appear as a single item. Otherwise, you could still import as an assembly and then export as a shrinkwrap which will produce a part resembling (and merging) all components in one part. From the assembly, File, Save a Copy, and then choose "shrinkwrap" as the type. From the dialog box that comes next, choose "merge as solid" and set a quality level for the export.