You can easily re-elongate trains without changing the existing times: Open the train data window (double-click on the train) and go to the Summary register page. Double-click there in the table run sections on the starting station of the first run section. Select the new starting station. Then close the data window with OK without making any further changes to the data. You will now receive the message "The route of the train has changed from station …", linked to the question "Do you want the program to automatically search for a new slot from station ... now?".

If you want to keep the existing path of the train in any case, it is better to answer this question with no. The train is thus given a blanket path between the new and the old starting station, which is calculated only on the basis of the travel and stay times (and surcharges) but does not take into consideration other trains. As a result, the red exclamation mark may now appear.

To avoid such a conflict without changing the original route, use the function slot search until -> next token exchange place (afterwards go on unchanged), which can be found in the context menu (right mouse button). Switch the route search to this mode and move the train path beginning with the new starting station upwards (earlier). Since the route search is always only to the next train station, the original route remains as long as this is possible in time (that means if you go far enough "up"). If necessary, you must repeat this action for several train registration stations.

Note: A route-finding function against the direction of travel of the train ("backward search") is in preparation, which simplifies such situations again.