With the number of users we have we did not want everyone to be able to see every other account that exists, unless there is a relationship or it is an admin account. I modified users.php, usr.php, and added the setting to the config. In the patch I made the config modifications to example-config provided .
Sorry. This patch has been superseded by a rewrite of the admin user interface.
I should add that I'd be happy to see another patch that provided similar extension, it's just unfortunate that this arrived in the middle of a big rewrite around this area of the code.