Chart appears here!

My kids are trying to register individually with their own emails. #1 son registered no problem, #2 son is not being allowed; the message says already registered.

Most likely the issue is that your first son has not logged out of the system. Before #2 son tries to sign up or in, make sure #1 son clicks the LOG OUT button at either upper right, or bottom orange bar in right column.

Participate as an individual, family, school class or group.