unable to add email under "ways to contact"

[MehgbynZI]

I am working for a non profit org setting up their learning management system. I am using free for teacher account.

I was shared with a set of emails and I failed to add more than 3 emails under "ways to contact" under "user setting" on the account.

there are members in team which need all access to the account to check progress and do the necessary task as per their role.

when I try to add the email, the dialogue form says "ID already in use for this account and authentication provider". I am however not aware of where it is being used.

Appreciate any help.

@ways to contact

@account