[keycloak-user] custom user federation syncAllUsers

I was checking the example for federation-properties-example. In both examples when you sync all users, it just checks for the users in the properties file and adds it to keycloak if it doesnt exist. If I want to do it both ways, so it adds users from keycloak to my database, and users from my database to keycloak. Should I add them here? I am not managing any password on my database, so i just need user id and username and maybe email. Also when I add a new user I can tell that syncronizeRegistrations() is being called but it is null. In order to create a new user in my database, should I call a create user function to my database here. Thanks,