Technically, anyone that wants to touch the car over the weekend needs to be registered as crew. It's for insurance reasons.
Anyone can come in for the weekend as a spectator. Show up, pay the $30 at the gate, hang out all weekend. Technically spectators are not supposed to touch the car, or tools, or anything that could hurt them. That said I've never seen anyone checking that those wrenching on a car had a crew wristband, but try not to push everyone's luck here. It'll only take one spectator dropping a transmission on their face to get the spectator rules drastically changed.
Edit: If you're trying to figure out how to register someone who does not have an email address (which, in today's world, how?), if you have a gmail account you can use a trick to get more than one use out of it. you can add "+WORDS" to your username on most webforms, and that email will make it to your account. Example, if your username is imd240zman, you can enter imd240zman+crew@gmail.com and it will come to your main account. Use something like that and enter all of their real information when you register them as crew.
20+ Time Loser
FutilityMotorsport Abandoned E36 Build2008 Saab 9-5Aero WagonRetired -
1989 Dodge Daytona Shelby 2011-2015 "Lifetime Award for Lack of Achievement" IOE, 3X I got screwed, Organizer's Choice