I would think photoshopping the bangs would be difficult, depending on your experience level. I woudl be a but nervous about it myself.
You could take them from another picture the family had of her with bangs, but that isn't a very realistic expectation, there are too many issues with that: quality of that image, the lighting, the size of the iamge and the ratio (size of the child in the frame).
I like the hat idea, or reschedule.