[keycloak-user] How to use two providers with same username in a realm/client

[Jansen, Gerhard]

Hello,

in our application I us an application specific user-database for authentication and I can also authenticate  users with their Active Directory credential (SPNEGO or  username/password).
Now we want to switch to Keycloak, but we can only use either a custom user-database provider  or an Active Directory federation provider in a realm. SPNEGO works fine, but form-based login doesn't.
Only the first federation provider is called. Maybe because login name for both providers is the same, even though neither userbase is imported.

How can I authenticate a user with a second federation provider with same login name, after authentication with first provider fails.
(Or do I even have to think in a completely different direction ?)

Thanks in advance for any suggestions.

Best regards,
Gerhard Jansen