A poster stated this several weeks ago--that she had just switched to joint, and there was no pull. I called Discover and they confirmed. They do not run the credit of the AU-becoming-joint. They figure that if the primary cardholder is willing to take the risk, it's OK with them. (Presumably because they can always come after that first person instead.)
I would call and ask them to be sure. When I first called several months ago, my CSR didn't even think that they had joint status.
* 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