Ensure both users have downloaded the Sectormentor app.
In order to add another ‘user’ to the same farm (on a separate device), login to the web app, and click on the ‘users’ tab on the left hand side menu bar.
When you create a new user, their passport is set to a default which you can change. Please make sure the new user then logs in straight away and changes their password to something that they will remember.
The new user will then be able to login to their phone, use their new password, and sync to that phone.