ok, well, I'm a bit late with a reply....
sorry for that, but- having looked at the photo, the simplest way to remove that shadow on her right would have been to have your subject push her hair behind her shoulder as that seems to be the cause. In order to leave her hair as-is and get rid of the shadow, then as Mark said, you would have needed an additional light either behind or over the camera or some fill from a reflector (which would probably have distracted that cute little dog).
That said, happy client = good job. :)
-diane
diane