Sounds like your sister could teach you a thing or two about braking...
She brakes less.
The pads probably didn't have much more than 1/4" to start with, and the slight lip is common on Audi rotors as they always run the pads slightly inboard of the edge of the rotor. On solid rotors, you usually get 1.5mm worth of wear, and vaned gets 2mm. a mm is a huge amount on a rotor that has only been on the street and one set of street pads.
Pads should have a groove down the middle, and from what you describe, there should still be a good deal before she even get to the bottom of the groove. Normal peaple can still get 10K or so out of the pads perfectly safely after the groove is gone.
I understand your concern, but it really sounds like it is a non issue.
My buddy Geoff can get pretty much anything.
http://seccs.org/forums/showthread.p...eoff#post46950
Also, the good old interweb.