I have a WordPress site called www.example.com; it has its own users account. Now I have created a sub site called www.yy.example.com. I have installed Multisite user management so that example.com site users can log in yy.example.com site. In yy.example.com I have restricted user registration in frontend; since users are registered by backend admin panel. In front end I have log-in form using frontend membership plugin. Now I want to restrict the access of example.com users in yy.example.com.
How to do this?