Im stuck this problem for couple of days, Lets check it out..

Site A:Social theme,Role:Subscriber; Site B:Job seeker, Roles:Candidate/Employer; Site C:real estate.Roles:User/agent/agency.and more!

what happen here is when user registered and login to site A will logged to B and C, but B/C couldn't recognize the role and this user not listed in B/C, this user will not able to see the contents at the dashboard, because the dashboard has assigned the page with different contents for different role; For example,at site B, user login as candidate will see the candidate contents at the dashboard; user login as employer will able to post a job etc;

Is there any solutions to let user from site A can select role when passby Site B or Site C, and saved this user to Site B or C. rather than needing to sign up with same email on site B and more.