Paul and I are always both named drivers on our car hire but I am the only Dollar Express member. Never been a problem. I do book the car hire in my name.
One thing to note - I signed my Dad up for Dollar Express with my credit card. Nobody said anything to them at the desk when they picked up their car. However when we picked ours up the next day the lady asked to check my credit card and she said to me 'you'll never believe this but some people sign up with someone else's credit card!!". I said well I signed my Dad up with mine and she knew that already - they'd let it go as they could see we both had cars book one day apart. However she suggested my Dad use his own credit card in future as it can cause problems.