This is something I often end up fixing in PS. I'll be shooting a family group of about10 adults 4 kids outside in the shade. I get the least shadows by front lighting with a studio strobe at the camera location through a large shoot through umbrella. Sometimes 2 strobes. Also a back light. I know there's a simple positioning of the front light to equally light the second row who'll be standing behind the seated front row ? High would seem good but I don't want dark areas under chins that I have to PP.