Just to be clear, you want to be able to drag a different path for each actor? How would they know which path is for which actor? Would you start by dragging from the actor you want to move? This is an interesting problem! I'm going to think about it.

Each path actor can have instance fields to (1) hold a reference to the Actor (unit) that it is directing (or an id code for the unit that the unit has a reference to); and (2) the next location to move to (where the next path actor is located, if not the end of the path). Then program the unit actors to first determine if the path belongs to it, then if so, save the location to move to next and proceed there. If none of the paths at any target location belong to that unit, then the end of the path has been reached. For an example (at least something that is similar), check out my Object Trail Following Demo scenario. It uses colored lines. Each actor follows a different color.