[keycloak-user] SAML IdP automatically link account

I have a SAML IdP that is used only for authentication and a separate database that contains information about the users, including roles. I've set up the database in User Federation and the SAML IdP in Identity Providers. The problem I have is that when users log in they are prompted to link to an existing account. This is confusing for them because from their perspective the only account they know about is the one on the SAML IdP. Is it possible to configure this Identity Provider to be "trusted" so that the accounts are linked automatically? I started looking into creating a custom authenticator based on the documentation and the custom authenticator in the example code but I don't see what the necessary steps are to cause the automatic account linking. Any suggestions would be greatly appreciated.