I was hoping it wouldn't affect that much, but my legal knowledge is limited so I wanted to make sure. It seems unlikely that her legal parents would have applied for a SS number in the two days before she was kidnapped, so that wouldn't be an issue. So it sounds like it would just be a matter of correcting some facts and then making whatever decisions she wishes regarding legal name changes. That makes the story much easier to tell as I can focus on the plot and not get bogged down with legal details!
Thanks to everyone who has replied!

