If you have a staff member in at your school who already has a login to Safeguard Record Manager at another school, you can't just give them access to your school's information. You need to create a separate email account at your school to be able to add them to your Safeguard Record Manager.
Sally Smith already has a login at her school with an email of email@example.com.
Sally is the temporary acting head at school 2. You can't add Sally with her 'school 1' email. You need to create a new email account for Sally, for example, firstname.lastname@example.org and use that to add her to Safeguard Record Manager.