Appointment Reminder support multiple users. There is no need to create a new account for each person in your business.
Click on Settings
Click Manage Users
3. Click Add User
4. Add the details for the new user. Make sure you are using a Unique email for each user.
Click save. You should be able to log out and log back in as the new user now.
If you just want to connect additional calendars go to Calendar > Add Calendar