You don't have to get a "fake smile that looks real". You get real smiles, and its your job as a pro to know how to do that. The large groups, you take what you can get mostly. A trick with large groups is to just act like a dancing idiot.... makes the kids laugh and the parent laugh. Whatever it takes.
With the single images, you can't cop out and say you couldn't do anything other than to say "smile". It's your job to know HOW to get real smiles if it takes you 50 shots to get em.
In any case, I agree about the cropping that will happen, but again, you can still have negative space on the left and right that can contribut to an image. Such as, when I see this field, I can imagine all of them holding hands and having a straight line throughout the middle of the composition. This is not dead centered, yet adds a lot to the picture.
Or as you did in 5 and have a pyramid sceme, which works nice. There are many, many options besides dead center.
I believe that many of these are good images, but lack compositionally and emotionally. I'm not saying this to hurt your feelings, I swear I am not. I hope it's not coming too harsh and that you take this all constructively. I am trying to help you so that you have things to think of the next time you shoot. I personally love when someone is this straightforward to me but if you are not likeing it, please tell me so and I will stop

Here's one play I did, (quick, 5 mins) might need to fix their skin tones and other things.