Why doesn't Melanie from "The Egypt Game" worry when people call April "February"?

Melanie is
not worried when people call April "February" because if the kids at school care
enough to call her by a nickname, it means she has been accepted. 

When April
first moves into the Casa Rosada, she acts fake and stuck-up.  Melanie, an exceptionally
perceptive child, understands that April has a difficult homelife and is upset about being
shuttled off by her mother to live with a grandmother she barely knows.  Although Melanie
herself makes allowances for April's behavior, she is worried that the kids at school will not
be so tolerant.  April insists on acting as if she, like her mother, is a Hollywood star, and
she gets "furiously angry when she (is) teased".  Melanie predicts that "to the
kids at Wilson, all (that) stuff" would make April appear to be "a smart aleck",
and her "wonderful difference" only "kookiness".

April is
indeed perceived as "an odd-ball" when school starts, but with Melanie acting as a
"go-between" to smooth the waters, the other kids eventually begin to accept her. 
When "two of the biggest wheels in class" start calling April "February",
Melanie knows that "everything would be all right...it (is) teasing, maybe, but not the
kind you use on outsiders" (Chapter 6).