First one I really want to know but can't ever find any information on is 'HOW' tell the train driver or even the AI train to 'GO VIA' a certain path in other words drive via 'UP main' or 'DOWN main' or passed a damn bridge or the Batmobile whatever!!! The second thing is!!! HOW in the world, am I supposed to add more locations??? There are routes with this option to spawn at random locations to create a scenario but it SEEMS like there's just no guide on doing this??? I've never found it.. Not even the idiots guide to route building
Use the Destination marker in the timetabling and set the speed to 1 and it changes from a Stop at to a Go Via, Or alternitavly use the little red flag as a hidden waypoint (Not shown in the F1 screen or on the HUD) You need to create a CSV with the locations and coordinates. A simple google search will give you the video i have linked below Train Simulator 2015 Tutorial - Route Building - Markers - YouTube
Route Origin is in every list because every route has a Route Origin - it is just different on each route.
An alternative method, which I use, avoids having to create a list of locations. (Its not as complicated as it sounds) Edit any existing scenario for the route. Press 9 for the map. Scroll, drag and zoom in to where you want your scenario to start and Ctrl-left click. In the top small 'compass' panel drop down, click the > 'Go' button. Right-click the map to return to the editor which will open at the location you have just selected. You should now be in your location Click the orange 'Scenario Tools' icon in the left centre panel and select your new scenario type. Place it in the game and click away 'Save changes to the current scenario?' - No (this means the scenario you chose to edit) It will then open in your new scenario for which you need to supply a name before it will allow you to save it.
There is no difference between the Player Train and an AI train in the game in that they all need start from, go via, stop at, pick up, set down etc. I did not see the 'Default for all routes' hence my reply - which post is that in?