ADManager Office 365 - Dir Sync and Source Anchor

ADManager Office 365 - Dir Sync and Source Anchor

Hi guys,

Just updated our AD Manager install so we can change the source anchor our Office 365 uses to DirSync but it only gives limited options to which Source Anchor you could use:
- ObjectGUID
- Userprincipalname
- EmployeeID
- EmpoyeeNumber
- SamAccountname

Was wondering if there is any way to select another attribute as the source anchor as we are not using any of the above as the source anchor.
The source anchor we are using is "extensionAttribute3"

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