I don't believe that this is an attribute issue, but rather it involves how references are made and maintained within an assembly structure. If this is causing problems in the sense that something which worked prior to NX 8.0 is now causing errors or giving you incorrect results, then please, as already has been suggested, contact GTAC and have them open an IR/PR so that we can get the right people looking at what you've encountered.
John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA