How come Anastasia is never included in the group of non Disney princesses?

Because Anastasia isn't Disney.

Anastasia is fox not Disney

When ever someone talks about non-Disney Princesses she is one of the first ones that are mentioned. It usually her, Odette, and Thumbelina (since she married Prince Cornelius). Its odd that anda would post this in a Disney Extended Princess club. Since its Disney and she is not Disney but 20th Century Fox. This club is about girls like Kida, Eilonwy, Jane Porter, Esmeralda, Megara, ect.