A shitty sketch of Epic and Chopin. They are close but Epics competitive nature makes her a lot more aggressive toward Chopin. While they got their cutiemarks at the same time, Chopin had a lot easier time getting into the music business than Epic. Epic did everything on her own while Chopin had help from his mother and aunt. As such, despite both of them being talented, Chopin's band is a lot more popular than Epic's solo act.
Note: Epic and Chopin have very similar cutie marks (though I haven't ironed out the details yet). They are both music based but their talents are slightly different. Epic can sing in any language cause she can understand how to pronounce words in tune with the music. Chopin can find the beat that matches the lyrics he writes.
The second pic is of Rainbow and Quibble's third (and last) child, Daydreamer or DeeDee as she prefers. She is the baby of the family and the loner. She very rarely leaves her room, often found watching anime or reading manga. Despite how lazy she is, she is actually a very successful manga artist. She has dozens of titles connected her myriad of pen names. Her brother is one of her fans, though he doesn't know she and that artist are the same pony.
Note: DeeDee is a mare with no interest in romance. She loves love (and many other genres) but finds PDA (public displays of affection) in real life either gross or pointless. She does, however, admire couples. They are interesting because they are so different from her.