TOPIC: Adding a Facebook Login

What file do I need to edit to add an option to use another module for a Facebook login, when new (or possibly returning) users are registering for an event?

This would have nothing to do with DT Register as you do not login to DT Register. You login to your Joomla website. There are Facebook login modules and plugins for Joomla. Just search the JED.

Thanks for the reply, Perhaps I stated this incorrect, DT Register can force the creation of a user account, at this point I want the option of using my Facebook account sync instead having the user create a separate account.

I do have one of the login modules, and it works well, just do not know where DT Register has the logic for the new account creation

The code for the auto-user creation feature is mainly in this file:

/administrator/components/com_dtregister/models/user.php

You can make your own customizations as you need, but note that we do not provide support for such customizations... unless you want to pay us to make such changes for you. Thanks!