"Please do not copy her homework for any reason!"
Translation:Bonvolu nenial kopii ŝiajn hejmtaskojn!
That would be a double negative, which is not allowed in esperanto. And if it was, kopii should be used instead of kopias. "please do not copy" vs "please do not copying"
It would mean something like "please do not copy her homework, if you have no kind of reason for doing it." which basically means "do it, if you have just a single reason"
You could then remove one of the negatives, but that wouldn't help you much.
"bonvolu ne kopii ŝian hejmtaskon por ia kialo" would be like "please do not copy it, if you have some kind of reason for doing it"
"bonvolu kopii ŝian hejmtaskon por nenia kialo" would be like "please copy it, if you have no kind of reason for doing it"