Thanks for your response.
Still a bit confused though....

As I am the primary renter of the car I have to provide my own CDW (if I don't want to pay Alamo's high rate for theirs). Through most Canadian insurance companies you can purchase CDW coverage specifically for renting a car (US or Canada). This is a $10, once a year, charge through my insurance company. I have purchased this before for my wife and I for trips to Vegas renting with Dollar and National.

But, we are going with another couple and I have listed one of them as an "additional driver". Of course, he is not listed under my $10 policy because he is insured elsewhere.

So........ my question remains that if he is an additional driver does he need to buy the $10 policy through his own insurance to insure that he is covered with CDW.