Hi Thomas. Yes, you'd do this by all sharing the same account. I notice you currently have a 2nd gen adapter set up in your car. If you're keeping that, then you'll have two apps on your phone. The original app will continue to give you access to your car and driving data. The Pro app will give you access to your sons' cars. Your sons will only see their two cars in the Pro app and not yours.
However, if you also update to Pro, all three cars will be listed in the Pro app and accessible to everyone sharing the app.
To get set up, each of your sons should download the Pro app onto their phones. Then log into your account in the first car and go through Setup. Once you're set up on one car, head to the next car and select "ADD A VEHICLE" from the main menu.
When you get to Crash Alert setup, since Crash Alert is connected to the vehicle and not the user account any longer, each car can have a different primary contact. So they can each set that up themselves from the app on their own phones by first selecting their car profile from the main menu and then selecting "Glovebox". They'll then go through Crash Alert setup which will verify their phone number to create the primary number and will allow them to add their own Emergency Contacts.