Drawing a line between attached counters

I want to place a marker with an “order” for a unit, and that marker can then be moved to a location where the unit is supposed to go.

It would be neat to be able to draw a line between the unit and its order marker. Is that possible? I imagine that the unit and the marker could share an attachment.

I have found a way: An invisible counter is attached to both, and an order from either causes it to execute a Send To from the unit the order marker, leaving a movement trail. If any of the two “master counters” move, they send a message to the invisible counter to clear its movement trail.if any of the “master counters” are deleted, the invisible counter is also deleted.