For purpose of Route Sharing, there is "Sharing" Picklist provided, which holds all GeoPointe Users, with whom Route can be shared by selecting user and clicking on "Add Share" button.
But when user base is large, and it involves different category of user sets, it becomes challenging to search user from Particular team or set and assign Route to intended user.
So there should be an option to Restrict/Filter users appearing in search within Sharing picklist.