First Broker Login flow - ability to link with existing users OOTB

It will be good if there is a way to configure First Login Flow easily OOTB, so that if duplicated user is found (Existing Keycloak user with same username/email like the user authenticated through identity brokering), he will be automatically "authenticated" and hence automatically linked to the existing Keycloak account without need to other verifications through email/password/other-broker .

Maybe it will need to be specify to allow this just for specified users (EG. users linked to specific userStorage provider or to specific "trusted" IDP provider).

The authentication flow shouldn't be done like this OOTB as it's not very safe for most of the deployments. However it should be possible to configure this without a need to implement custom authenticators (which I believe many customers already did for this use-case).