Re: Using a different name at school. My niece, Greta, decided when she started kindergarten that she wanted to be called Margaret in school. She likes her family to call her Greta still, but felt like she should use her formal name in school. She made an announcement to our family; it was pretty cute. It's only confusing when, at her birthday parties, everyone in the family sings "Happy birthday, dear Greta" and her schoolmates say "Margaret."