It is also possible to add stops to a route (i.e. reroute the route). You can do this at the beginning or end of a route, or have a reroute in the middle. First, create a Reroute modification, and select a route and patterns (as before). You then select the start and end stop of the reroute (i.e. where the route begins and ends its deviation from the its existing pattern). Note that you will need to select patterns appropriately and create one reroute for each direction of the route; a reroute can apply to multiple patterns in a single direction as long as they both contain the start and end stop in order. You select a stop by clicking the select stop button, and then choosing the stop on the map. If you leave the from stop blank, the entire route up to the from stop will be rerouted. If you leave the to stop blank, the entire route after that point will be rerouted. This can be used to extend routes, or to divert the ends of routes (e.g. to new rail stations).
You can then edit the alignment and the intermediate stops by clicking on "Edit Alignment." This uses the same tools that are used when adding trip patterns.
This modification is displayed on the map with the route being modified in gray, any segments that are being replaced in red, and the new segments in blue.