Never noticed her! But she could very well be the Snow Queen; she looks a lot like the Snow Queen's daughter would look. She hasn't been introduced in Ever After High, so we don't know for sure. I l’amour her design though! :)
toi are correct about this "snow princess" being in plus than one episode. I think I saw her in "And The Thronecoming Queen Is…". But the Ever After High Wikia considers her a backgrounder so she's not the real Snow Queen's daughter.