may be need to redirect one form , add email ,after login with Social authentication first ,then system register one account .
workflow:
1 user chose login with Social authentication
2 user login at Social authentication website success
3 third Social authentication web site ,redirect back my site
4 but the teturn info don`t contain an email,
5 my system redirect one page , let user fill email info at one form,user submit
6 system regiser one account with the email,Social authentication account . show succcess to user
7 ok.it is ok
may be need to redirect one form , add email ,after login with Social authentication first ,then system register one account . workflow: 1 user chose login with Social authentication 2 user login at Social authentication website success 3 third Social authentication web site ,redirect back my site 4 but the teturn info don`t contain an email, 5 my system redirect one page , let user fill email info at one form,user submit 6 system regiser one account with the email,Social authentication account . show succcess to user 7 ok.it is ok