When creative hallowverse I had made Twilight and Sunburst have twin foals, a Pegasus male, and a Unicorn female. However after playing around with the designs, I decided to give them a 3rd child who was a little Earthpony female. So that they had one foal of each race due to Twilights Alicorn anatomy having traits of all 3 species.
 
Since Sundance doesn’t have a horn, she was born with a diamond-shaped birthmark where a horn would be had she been born with one.
 
Sunburst is a big softy about all 3 of his babies. Especially Sundance because she’s such a wee little thing.
 
 
May add a story bit to this post at a later date!
 
 
Twilight/ Sunburst/ MLP (C) Hazbro  
Art/ Hallowverse/ Sundance (C) Eve-Of-Halloween