Appointments+ social registration

Hi,

I use Appointments+ in multisite installation. At the moment, when a user creates a website (blog), he has the ability to enable registration with Facebook, Google+, Twitter in Appointments+ settings. So every user can register in my multisite network without accepting my network service terms of use and I have no control over it!

This solution for multisite network is not good:
1) User registered without accepting the terms of use of the service, so I can't rely on the service terms of use.

2) All the countries of the European Union required approval processing of personal information by user (EU Directives), otherwise the website owner can get a cash penalty. So the user must accept the terms of use.

3) When the user signs up with for example facebook on one of the sites in multisite (and he does not notice that site is part of the netowrk), then after he want to normal register with wordpress, he will get information: this address email is already taken.

Regards,
Thomas