I would carefully cut the head off right above the collar.
Maybe you should do this when you stepdaughter isn't around. I know you said she's taking this pretty well but how will she handle a decapitation?
Is it possible to cut out the remaining face and put it on a light box so you can trace the features?
Maybe it's because it's late and I can't sleep but this is starting to sound kind of gruesome. Just have to remind myself we're talking about a doll here. I'll be interested to see how you solve this problem.