The friend you speak of that is not approved cannot visit without prior authorization. Your inmate may add or subtract potential visitors to his list as often as he wants.
https://www.inmateaid.com/ask-the-inmate/my-boyfriend-is-in-the-city-jail-and-has-a-list-of-approved-visitors-if-a-friend-not-on-that-list-wants-to-visit-is-he-able-to-make-changes-to-this-list-could-his-friend-come-with-an-approved-person-to-visit#answer
Accepted Answer Date Created: March 31,2013