My step-child was sent this email today by her mother and I want to know if it is reasonable. To put it in context, we are a conservative family where calling parents by their first name is unthinkable and other adults are either known as 'Mr / Mrs' or 'Auntie / Uncle'. That is our lifestyle choice and should not be the focus of your response:
......you have still been calling your step-mother 'mummy'.
I have already dealt with your younger brother as I saw a chat he was having with his father, where he refers to her as 'mummy', which she is not, and will never be, and when you return home, I'll deal with you, because I was under the impression that you understood how wrong it is for you to call anyone else, but me, 'mummy'. So, we'll be chatting about this after school.