First Name V.S. Middle Name

Now, we need to talk about names. I know that sounds confusing, but it will all make sense. We'll be using my daughter, Cotton Candy (and Clarity, Twilight, and me) for examples. Throughout the MLP Next Generation stories, Cotton Candy is called just " Candy" for short. My problem I have is that they call her by her middle name. Throughout the show MLP though everypony is called by their first name. I mean do you ever her somepony call me "Pie". No, you don't. They all call me "Pinkie" and they don't say "Sparkle" they say Twilight ( same with Rainbow). In this case, my daughter's name should be "Cotton", this goes the same for "Crystal Clarity". I know that we all want to call her Clarity over Crystal though, so, I decided to change her name to "Clarity Crystal" instead of "Crystal Clarity".