Cheerleading Image <Advice needed>

I mainly shoot sports so portraits are a different animal for me. Plan on taking individual shots of my daughter and some of her friends. I will be using my tamron 28-75 (hand held) from about 15 feet away. The girls will be positioned on their knees with pom poms in front. I am trying to determine the best aperture to utilize ? I was thinking f/4 but now f/5.6 since I want to ensure images are sharp .

I just took pictures of my daughter's team last Friday. I used f/3.5 for most of the full length shots and the DOF was sufficient. That said, if you don't have a busy background you'll probably want to stop down to get some additional sharpness out of your lens. My experience is here: https://photography-on-the.net/forum/showthre​ad.php?t=552000

I hope it goes well!

Sharpness is more determined by your shutter speed and at what speed you can effectively hand hold a shot. I'm not so steady so I try to keep mine at 1/160 at the lowest point.

Aperture depends on if the girls are in a straight row, or staggered... You want your DOF to be deep enough to emcompass the entire scene. I'd stay at f6.3 or more to be on the safe side... especially if there are like 3 rows of people.. f/8 is always nice, but that may be determined by the amount of light available to you...

Have you tried looking at a DOF calculator?