I have an ArcGIS for Server feature service with points, polylines and polygons in my Web AppBuilder map application. With the Edit Tool, I can split and union my polygons. With the Edit Tool, I can split polylines, but the Union tool does not seem to work on polylines. Should the Union tool work to merge two polylines into one like I can with Union on polygons? The polylines have been "snapped" so their ends are touching.