It would be great if you could use different elevation layers for different scenarios of an project/plan. While editing terrain might be a bit too complex for ArcGIS Urban, different terrain is something normal in scenarios in CityEngine. As an user it would be expected that different scenarios would be able to contain different terrains/elevation layers in ArcGIS Urban as well, but the editing of the elevation layer might take place in ArcGIS Pro or CityEngine. It would be very useful for a city planner.