map users

I would suggest using the JFBConnect backend > Configuration > General > 'Automatically Link Users by Email' setting. If a user logs in via a Social network for the first time, and their email address is already in use by a Joomla user, map the user to that account automatically. If you have already tried this setting and are having problems, please provide details on how to reproduce the issue.

When a social login occurs, a normal Joomla account is also created at that time. If a user attempts to register a new account with the same email address, this will be prevented by Joomla.

I hope this answers your question, but let us know if you need more clarification.

-Melissa

The "Automatically Link Users by Email" setting Melissa describe above is what you're looking for. In the case you describe, after a user registers with a Joomla account and then later logs in with a social network using the exact same email address, the social account will automatically be associated with the existing Joomla account.

I hope that helps answer your question,
Alex