[keycloak-user] Twitter login via keycloak

Hi All, I have a requirement where a user who has registered his mail id manually should be able to use twitter for login using the same mail id. Is this option available. To elaborate Using gig(a)gmail.com mail id I register to keycloak manually. Now I wish to login to keycloak using the same mail id gig(a)gmail.com but using twitter instead of manual login. Is it possible? When I try doing that, I get an error saying "Email id already exists". I wish to login using same mail id via facebook , twitter and googleplus. How to go about this? Thanks, Jayapriya Atheesan