Time Machine and the dreaded negative sign

Yes, it's scary, and yes I'd be worried. Why doesn't bob already own his own backups? If it's because of a UID or UUID mis-match, what's preventing recreating this problem (perhaps in reverse) in the future? If you can risk damaging the live machine I'd rather change Bob's UID and UUID on the live machine than on the backups, on the theory that there are probably other UUID mis-matches lurking on other disks.

In any case, scary as it is, if I were to try to fix I'd use the Finder if it were just a few folders that could be fixed with "Apply to enclosed items...". If that was impractical, next thing I'd try would be to find files owned by whoever currently owns Bob's stuff and change only those files. Going off of file path seems kind of risky to me.

I almost ran this script after i replaced my system drive with an SSD and my new user uid was different to the old one (wonder what happened if you ever did run it?).

In the end i found http://pondini.org/TM/B6.html (again) and the "tmutil associatedisk" tips seems to have worked for me (on Mac OS 10.7.5) - fingers crossed!