Display only authors on new post creation

Hello!

I have just few users set as authors in my site, but when I create a new post for a diferent author user, on choose author it lists my intire base of joomla users.... thousands of users. It makes really dificult to find the right author, even using the search tool. It is imporssible as well to simple write the author username in the field, what would make things a lot easier.
How can I restrict the authors list showed to display only joomla users from author group?
All other users are on group "registered" and ACL configurations on EasyBlog are all options denied.

Thanks in advanced.

Adriana