You could always try, but it's unlikely. I don't know that they would re-open with the old date for the true cardholder, much less for the AU.
I do remember a post that Discover had allowed an AU to convert to full at the death of the actual cardholder, but of course, the account was still open at that time, with the AU still on it.
It's worth a call. Although I know that many get annoyed by their product pitches, I have found Discover's CS to be up among the top few companies.
* Credit is a wonderful servant, but a terrible master. * Who's the boss --you or your credit?
FICO's: EQ 781 - TU 793 - EX 779 (from PSECU) - Done credit hunting; having fun with credit gardening. - EQ 590 on 5/14/2007