>> One is allowed to lie (or better yet change the truth) for שלום
There are bunch of caveats to that. One is from Besht – if you inappropriately lied at least once in your life, you can’t do it. So you got to be either 100% honest or a litvak to use it…
A child should not do it until he mastered the art of being completely truthful, and you should not do it in front of a child (Story of Rav and his wife sending him wrong dish, and the son “correcting” the order). May apply to some here.