Linked Annotation

This “how do I” is primarily born from my question about multi-click annotations. This could also be it’s own topic so here goes:

How do I link annotations so that when the X2Y2 of line1 moves, X1Y1 of line 2 will move? Doing this in one direction I’ve been able to do. However, when I move X1Y1 of line2, line 1’s X2Y2 aren’t updated so they separate. Ideally, this should probably be event based. Is there a way to subscribe to the movement of the handles of a BaseAnnotation? My annotations are created dynamically so the linking method would need to be run time compatible.