Hiding user list from other users


I have an RT v 2.6.1 installed on our server and have a question about
users rights.

We need for now to restrict some users to not see for them a list of
another users registered at the RT both in proposed list to
change owner, and in the search of users by an email or an other thing.
But we didn’t found out how to realize this in context of the
installed RT.

So quiestion is that does the RT support hiding user list from other
users? If not, is any modern version of RT that does it? And finally
how can we patch the installed RT to support the feature?

Sincerely yours, Pavel