I am trying to solve this design question for my class. The problem is simple - there are thousands of users and I have to design a UI that lets you associate them with a group.
I found this question Multiple selecting widget options, which uses a shuttle widget that lets you select multiple users from the left panel and add them to the right. This action defines them as members of the currently edited group. However, my instructor's feedback is that this is not user-friendly in the case of a long user list. Too much time would be spent scrolling to find the users you want.
Is there a radically new way to do this? I was thinking of adding filters on top to directly access users by name, organization or any other attributes to avoid some scrolling on the user's part.