You can find this information when you login to your account here, and click on "My Account" then go under Current Reservations, you can click on the camper reservation and then click on each of the camper's names. 

Once you're on the right camper, you can scroll down to the bottom of the page and you'll see persons authorized for camper check out. 

You can add up to two names and two phone numbers for those names for each camper.