Have her see an orthopedic doctor and get assessed for a Bankart lesion/inferior glenohumeral ligament/inferior labrum tear.
http://orthopedics.about.com/cs/gene.../a/bankart.htm
Shoulder strengthening may help (I'd start with rotator cuff work and move onto to isolations then compounds) but depending on how bad the dislocations and instability are it may require surgery especially if your client wants to work out at any decent level of ability.