Thank you, @waylow 😀! I’ve downloadad the file from Dropbox and opened it with Blender 2.90 which I use for editing my Piero. The “Relationship Lines” to the “Root Bone” are displayed. Did you maybe turn off their visibility in the “Overlays”?

The wings are now completely rigged with all “Constraints” and “Drivers” in place. Next stop is the completion of the left leg’s rig here.