Could be that she just needs to strecth out the muscles on the front of her body. Lats and rotator cuff muscles can play a part as well. If you have her stand in facing you do you see the backs of her hands or the sides? If you see more of the back of her hands that means she has some hypercontracted muscles (most likely pec major/minor) pulling her shoulders and arms forward wich can limit flexibility. Many computer types have this sort of thing from being hunched over in front of a computer all day. With some stretching and massage she might be able to reach her entire back eventually
