OK. I use my own qa-external-users.php. It works fine.
BUT if I set on "master site" a user as "blocked", then he can't post but can read and downloads.
I talking about all the attached files that I was upload to my server.
All files that can be downloaded.
May be there is other way to control users rights? To show or not some content.
To allow or disallow download from site.
May be I can make a new group with limited rights: no read, no write, no downloads?
As if it is unregistered.