My wife tried to sign up for Avis Preferred using a credit card for which I'm the primary holder and she's an authorized user. I use that card for my Avis Preferred account. Avis told her she has to use another credit card, as two accounts can't use the same credit card.

We'd like to use that card, as it has the best benefits. Should she just sign up with another credit card, then show our favorite card at the counter? Is there a better way?