Single signon defaulting pre-fill to UserPrincipalName , would like sAMAccountName

Hi team,

We have an active directory / LDAP integration for in-house staff as well as a custom database for externals

When the internal user types their email, it recognises the credential and sends them to SSO ( see picture 1 )

On the new SSO login screen, the user ID defaults to the email address, ( see picture 2 ). They then need to delete the @domain.net.au to be able to authenticate ( see picture 3 )

It is not the biggest issue for sure, though it does cause some internal noise, Is there a way to default the pre-fill on the SSO screen to the ‘nickname’ or the sAMAccountName’ attribute - rather than what I assume is defaulting as ‘UserPrincipalName’ ?

Picture 1
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Picture 2
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Picture 3
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Thankyou for any help
Paul