Maybe I found the answer.
- All the domains in my db was imported from external sources, and the importing utility (mydnsimport) does NOT set the permissions. So nobody but the admin can do anything on that entries until you manually set to "riud" the permissions as I described in my previous post.
- MyDNSConfig seems to work with group criteria rather than with user criteria. So when you assign a domain to a user, MyDNSConfig change only the sys_groupid value in the db.
So, you can create more users in a same group and manage the DNS zones belonging to that group.
I'm a little bit confused about relations between "Clients" and "Groups". Creating a client seems tho be only a "shortcut" to create a user and group at the same time ...
Hope it helps.