This is like, a headcanon of mind.
It's just who I like to think Derpy's family members are.
I had all of these planned out except for who her mother would be. So, I went through a list of background ponies and found one with the closest color scheme to hers. Her name is Graceful Falls. And I think she only appears once. And it only shows the front half of her so I just made up her cutie mark.
Derpy's baby sister Dipsy. A baby unicorn that appeared in Baby Cakes, who has the same color scheme as derpy.
Her father, Mr. Zippy. He is in the episode Putting Your Hoof Down. He's a grey mail pony with bad eyesight, so I always thought he could be Derpy's father.
Hugh Jelly, the pony who's strangely obsessed with tubs of jelly. I've always thought of him as her brother. Also, I didn't know what his cutie mark is (it's probably jelly) and I saw a picture someone drew of him with bubbles for a cutie mark, so I just drew that. Because I didn't feel like drawing a jar of jelly.
Then there's Derpy.
I like to think of Dinky as Derpy's sister, not daugher. Derpy just seems way too young and innocent to have a kid. Plus, in Equestria Girls, she's in high school.
So, I just really don't like the idea of her having a daughter. I honestly didn't really want to include Dinky, because I kind of think she is Carrot Top's daughter. They are seen together a few times. Also, Carrot Top seems to be in a relationship with Written Script or whatever his name is, so I think they are her parents.
I didn't include the purple unicorn (Sparkler I think her name is or Amethyst Star) who was with Dinky in the Sisterhood Social. Because, well she's just a completely different color from the rest of these ponies. So lets just pretend she is Dinky's foalsitter because she is also seen with that other filly in The Mysterious Mare Do Well.