Just a quick reply, I would think about checking out the trigger points in the cervical/th/gh muscles and review her posture/shoulder balance etc. See whether treating the trigger points changes her comparable signs/objective markers.I have have had great success from looking really closely at the soft tissue. Look at the muscles in the static postural position (cervical and thoracic and its relationship to the shoulder) and then look at the same muscles during dynamic UL movement. Clear Rib 1 and the thoracic outlet.
Good luck.