allow page jumping or searches on group manager lookup

the group manager page on Manage groups only lists a small list of individuals, so if the groups are a shared group for the district and we need to make changes, we have to manually go through the pages to get to edit the group manager settings. when a new group manager is created, he did not come in with "Allow Requests On Behalf of" checked off, which required manually navigating 20-25 pages of users, rather than searching for the user I was looking for