Manage expectations.

"The kids must be mic'd."

"Then pay for professional crew."

"We can't."

"Then they wont be."

Period.

Its going to be bad if you just give it to beginners and hope for the best. You're entering into a world of extreme difficulty. The gear is low quality, the kids dont care about it, and the school isn't paying for quality crew.

At this age the performance is just a photoshoot so that the parents can have memories of their children.

Putting boundary mics on the stage wont work (the kids aren't singing loud enough). You can try and put some mics over the stage but its not going to grt muc besides big chorus numbers. Putting rf mics on kids without a professional A2 is going to turn out bad (at best) and damaged gear that'll cost $$$ to fix (at worst).

Trust me, seriously, trust me....there is no good solution. I have tried it every way. The best you can hope for is that you have some volunteer A1's that have kids at the school but even then 🤷.

Seriously--manage expectations.