How can I link BOM item numbers to stacked balloon for multiple versions of an assembly part?

Example:

The assembly has 4 different configs. The difference between the configs is the config of one of the parts. Because the differences are minor and th eparts look pretty much the same I just want to show one, with a multiple balloon saying item 2,3,4 or 5.

So far the only way I thought of was to add all 4 configs of the part in, hide 3 of them - then I can access the balloons and stack them by selecting "origin" for each instanced config separately in the drill down list. That seems a bit long winded though...

SLDWX files attached in the zip.