“Mommy! Daddy! Look! I got my cutie mark! And its for magic! Does this mean I get to go to Auntie Twilight’s school for gifted unicorns?”  
Its funny how many people missed the fact that Luster Dawn was supposed to be Starlight and Sunbursts daughter. I mean look at her. Her fur color is exactly what you’d get if you combined golden orange with light purple, Same with her mane which resembles her fathers hair color but has the signature off color stripes of Starlight. And of course her cutie mark looks EXACTLY like sunbursts.  
My thought of why she didn’t know that the mane six were still friends is that after getting her cutie mark she moved to Canterlot to attend Twilight’s school for gifted unicorns (Like what happened with Sunburst) and so she wouldn’t have really grown up around the mane six, other then Twilight, and let’s be honest Starlight was kinda Twilight’s friend. Not really a part of the mane group. Anyway thought I’d point out the obvious which no one other then myself noticed with a cool picture. Enjoy.  
Jade A Green.