Dynamic components: "sticky" angles/axis

I’m trying to model a climbing wall with a overhanging top part that I can click on to change the angle of both panels or just the very top one. The problem I’m having is how can I change the angle on the bottom one so that the top one will move with it but keep the angle?
Ideally I’d like to be able to click on the bottom one (Panel1) to change it’s angle while dragging the top one (Panel2) along and then click on the top one (Panel2) to just change it’s angle.
Any help is much appreciated!

Selectable wall angle.skp (445.0 KB)

To have the objects move together, place one in the other like a hand and arm is part of the arm. In this case, I move the top side plates as well as the upper panel and set (locked) all sizes first as the rotation will cause a scale as well.
the on clicks need to be on same level so moved the upper movement on click to the lower hinge plates.
Selectable wall angle.skp (441.0 KB)