There's a few options. Both of the ideas below require that you disable the "Enable Automatic Registration" setting in JFBConnect so that the user is brought through a form-based registration. Once that's done, you can:
* You can set the "Registration Component" of JFBConnect to "JomSocial". That will let the user authenticate through a social network, but bring them through the registration flow of JomSocial and prefill any information out from their social network profile.
* Set the Registration Component to "JFBConnect". That will go through our registration flow. In the Profiles area, you can choose to show all JomSocial fields or just the required ones. This is usually a quicker registration flow, but with lots of fields, it doesn't look as good.
I hope that helps,
Alex