回复：我只是陈述了发生了什么，我的看法和建议。至于校长怎么解决，是老师还是parent volunteer

I read the school reply again, you are right. The pricinple did say that they will supervise the line, that's good!

You did the right thing. In general, we don't need to feel  没必要指手画脚, as long as people intend to help, the suggestion can be considered relatively easier.