Great. So in that case, I think your best chance is to use the left side of the second photo (including the bigger girl) and the right side of the first photo (including the smaller girl) and have the blend between them.
I can see why you prefer the little girl in the first photo.
But is there a reason you prefer the big girl in the first photo? She looks nice in both to me.
I'm so sorry, there's still no better method than the one I first described. You'd need to work patiently on a dodge and burn layer to get rid of the rest
I think this is perfectly feasible, it will just take a LOT of patience. A lot of borrowing tiny parts of the three to form a 2, lots of tiny cloning.
I made a bit of a start: