Remove Shadows From Group Photos

I have 12 group shots of students where the lighting has cast noticeable shadows directly behind some of their heads. I need those shadows taken out while leaving every other part of the background exactly as it is—no colour changes, no extra cleanup, just the shadows gone.

Please work non-destructively in Photoshop (or your preferred retouching tool) so the original texture and detail stay intact, and return each image in the same file format, resolution and dimensions I supply. A fast turnaround is essential; let me know how quickly you can complete all 12.