Hi Thomas,
Thank you for your reply.
This use case is for registering. Users do not have an account yet. We offer them to sign up with a social provider. In the first step we ask for their email, this will be the username for their new account. Afterwards we redirect them to the social provider where they authenticate. This social provider will be merely an identity they can authenticate with but the actual username is something they choose themself and we want to do it beforehand (UX designed it that way).
When I ask for the email and redirect them to the social provider I lose all context, I have no way of telling what the user filled in in the first step.
I tried using regular sign-up from auth0 and create an account in the first step with the email they provided and afterwards try merge it with the social identity that gets created but I have no way of knowing which identity to link, I have nothing to match on. I would like to match on the email they have first provided but that seems tricky.
It is a bit like the solution here Signup with username & social connections but I need a way where I can ask for the email first and then match it with the social provider afterwards