You can use the same email address, you'll just want to change the Scout name in the invite each time. Please also note, Scout families can simply register an account at www.trails-end.com without receiving the invite, they will just have to pick the council, district and unit when they register.
For more information on inviting Scouts, please refer to the training video below:
• Unit Info – 7:39 – 11:54
o Invite a Scout – 8:06 – 8:42