It is so much harder to be quiet in a situation like that - wow, good luck! We all need our fidget place to survive!
A few thoughts: first of all, perhaps that ASM is overcaffeinated - she shd make a point of avoiding anything to eat or drink with caffeine for the duration. And she needs to make sure she stays out of the director's eyeline as much as possible.
But this is also a great opportunity for her to find that stillness place inside - because she is gonna need to find the discipline to stand still and hold it in backstage for the sake of the actors once the show opens too. Yoga maybe? Breathing exercises? Even just clenching and releasing to get her muscles to let go and help her learn to just sit still...?
It's a real challenge (and believe me, I know!) but it can be done - but it takes work and constant awareness.
And good luck with tech, when you will all be chattering on headset! (yikes!) - at least when the director moves on and it's your show, you will be able to shift around without getting smacked!