I can’t add my kids if they don’t have their own email address but I don’t see any valid reason that they need to have their own email just to use typesy.
Each user needs a unique email address to set up the user account. This will be helpful in case someone forgets his/her password because the software will require entering either username or email to reset the password. If your kids do not have their own email addresses, you can use a dummy emails to create the user accounts. Just make sure to keep a copy of their username and password for future reference.
Community Associate at Typesy