Oh, this is always tricky.
You need to begin by cloning the people out of the darker photo. So that it's just a photo of scenery, you know? That removes a lot of the difficulty of "lining up".
All the channels are too damaged for any kind of "rescue" of those areas. It'll just be painstaking cloning, and/or swapping in areas of detail from another shot.
You don't need new prints. Of course your lab don't change they way they print just because one of their customers got a new calibrator.
Please check the prints you already have.