If you only want to control what goes on top of what and you don't want anything on top of all else (e.g windows), then loading order is the best way.

First module loaded goues on top of the next module loaded and so on. So if you want your shortcuts on top of your labels, load shortcuts2.dll before label.dll.
If you want one shortcut over another then define that shortcut before the other (the file is read top-down). I don't know if this works for labels. But something should control which goes over what, so try experimenting with the label list defining the one you want topmost first and things like that.

I don't like using ontop-bangs since then your labels or shortcuts will end up on top of everything, but maybe that's what you wan't. If not, then as I said experiment and use loading and definition order to control ontopnes.