How might I configure a login scheme where by
- if someone already has an account on the site they may associate a FB account and login with it
- But yet, deny login to any FB account that is not already associated with an existing account
Is something like this approachable?
In other words, I don't want random FB accounts to log into a Drupal instance but yet, want to allow existing users to associate a FB account with their Drupal login.