As you already know, you'll have to experiment with your girlfriend.......'s stance. Though less stable, narrower will definitely make turns easier. Also, a bit of setback can help too. Remember, change one thing at a time and take a few runs. Write down where everything is now so you can keep track of changes. Who knows? The previous owner could have been a total kook.
Curious, are all of her turns hard to make? Or is she having trouble with one side? Technique can play a big part, too. Soooo many variables.