Hi to all the people on this forum!

I hope this subject has not been already posted, I didn't find any similar topic.

I'll rapidly explain my problems:

I created a WP installation to be used as a private collaborative space, with many groups of users; every user should be able to write articles and let other users in the same group read and comment them. I gave every user the Subscriber Role.

Here comes the first problem: only Administrator, for what I can see, is able to decide which groups of readers and/or contributors can read articles; other users cannot do that. So I set article reading as a limited role; now users can write their own articles, but only themselves can read 'em. No other user, even in the same author's group, can read his articles.

So how can I solve this? Setting all users as contributors is not a good idea, because this way any user could read any article (by the moment, also contributors CAN'T set reading limitations on their articles).

Is there a way to let other users than admin "protect" their posts, limiting posts' reading capability only to same group's users? Is it possible to do it from WP/RS administration, or have I to tweak the code?

Or could it be better (this idea came to me a minute ago), to have a WPMU installation, creating each "group" of users on a single blog?

Please help me, I'm going crazy with this

Thanks a lot,

Daniele