Routing for pilots.
Between location A and location B, the routes should be drawn as a line.
This should be movable between A and B to be able to select other places in between.
This would be very useful for pilots.
If you mean the Route planner, this is possible. Just click the line between A and B to add waypoints.
But if you talk about the Flight planner which is in the plugin list, it seems not possible.