@SunnySide  
Yup. Her name is Golden Harvest and her nickname is Carrot Top.

@Squirmy Hooves  
You mean carrot top? :V

@SunnySide  
Golden Harvest is the yellow-and-orange Daisy recolor with a carrot Cutie Mark who is seen in fandom as Derpy Hooves’ room-mate.  
Sweet Wheat is a background Earth Pony filly who was seen with many different Cutie Marks in different scenes. She was in a pink princess dress for Nightmare Night.  
They were shown racing together in Sisterhooves Social.

@Squirmy Hooves  
Okay you lost me. Who the hell is golden harvest and sweet wheat?

@SunnySide  
Exactly!  
The fandom did not pick up Cloud Kicker being Alula s’ sister, Berry Punch being Piña Colada s’ sister, or Golden Harvest being Sweet Wheat s’ sister.

@Squirmy Hooves  
Or you’re trying way too hard :>

@Background Pony  
Or Dinky was not really racing with Amethyst Star, but the background pony models were used for the other sister-racers because the sisterhooves race was not given enough screentime to introduce the other contestants. If we had a new Sisterhooves-based episode with more screentime for the other contestants, we may get completely new ponies as contestants.
 
 
Trough, i myself see Amethyst Star as being Tootsie Flute s’ big sister, Bon-Bon and Lyra s’ daughter who was conceived in Doctor Whooves’ TARDIS, granting her Time Pony genes and a second-family connection to Dinky, Derpy, and Doctor Whooves. Now, Amethyst Star lives with Derpy’s family.

Oh now would you look at that.
 
Sweetie belle is Applejacks sister!
 
It’s canon!!!!

My headcanon is that Amethyst Star is the number one foalsitter in Ponyville, and is a kind of big sister character to many of the fillies. She can be seen in the Mare Do Well episode having a picnic with Tootsie Flute as well. So no, these two don’t necessarily need to be sisters.

I’m gonna change things up a bit from the slowpokes.  

DAMMIT OP Y U NO SPOILER!?

@MLP-Silver-Quill  
Maybe is a robot pony toy that is custom made for lonely mares who don’t have a family.

Dinky also has three different cutie marks and is a blank flank. Depends on which episode your watch or how she’s feeling that day.

You know its possible that not every pony that participated was a literal sister to each other.
 
Just sayin.

@RIG
 

My headcanon is that Amethyst Star is more like a mentor, since Dinky doesn’t have another unicorn in her actual family. And since they let Applejack and Sweetie Belle race together, we know they aren’t necessarily strict about teammates having to be biological sisters.

cannot post sloepoke images on a 3ds…  
please someone else deliver

Uh, yeah. That was in season two i believe. A long time ago :/

The other post is just a suggestion. No need to retaliate, OP.

nowai

And here come the “Slowpoke” images…