@CMC Scootaloo
 
chirpy is crackle pop…….

@Background Pony #8D3D
 
That’s kind of the same problem like with Crackle Pop. If she lives in Ponyville, why has she never been seen in over three and a half seasons? And why still not during Season 5, Season 6 or now in Season 7?  
Ponyville isn’t that big, we should have seen every citizen of it (minus those who quite recognizeably moved there later, like Peach Fuzz, Lily Longsocks or Coconut Cream) at least once up until Season 4 already.
 
And for Crackle Pop, this still does not explain why he hasn’t been seen again since “The Cart Before the Ponies”.  
The fact that he exclusively showed up during a special sports event, one that most likely many ponies from other towns attend, too, because it’s famous, adds further evidence that he is not from Ponyville.

@CMC Scootaloo
 
I thought that Chirpy was just visiting Rainbow Falls and Derpy was off screen at the time.

@CMC Scootaloo  
True, i’ll give you that, I just like the theory that Derpy has the most foals in Equestria

@infinita est lux Solis
 
Sounds awful. Even lower-class citizens wouldn’t leave their foals behind, especially not Derpy, even though that means they have to cut back on food and share it together.  
Derpy’s not so awful to abandon her family just because of money issues. It troubles me seeing someone who would come up with such a theory about her to justify their belief that Crackle Pop and Chirpy are her foals.

@CMC Scootaloo  
Don’t know, but I usually think of Derpy as a lower class citizen, perhaps she didn’t have the money to care for three foals…

@infinita est lux Solis
 
Grandparents? Why would Derpy leave two foals she’s the mother of behind at her parent’s place, if Chirpy and Crackle Pop would be her foals?

@CMC Scootaloo  
I thought that perhaps Derpy was born in Rainbow Falls, Chirpy and Crackle stayed with their grand parents, while Derpy and Doctor Whooves went to Ponyville, where Dinky was born…

@Background Pony Number 17
 
Crackle Pop was never seen in Ponyville before….. It’s awfully uncreative and also mind-numbingly nonsensical to assume he could be Derpy’s son, when he was never seen in Ponyville before the Applewood Derby we saw in “The Cart Before the Ponies” during Season 6.  
Seeing that he obviously came from somewhere else to participate in the derby, most likely Rainbow Falls because of his resemblance to Chirpy Hooves, he is more likely Derpy’s little brother. And by extent Chirpy’s brother, too.  
But son is completely impossible, after five and a half seasons full of background pony appearances where he has never been seen in Ponyville even just once.

@Background Pony Number 17  
Well yes, except rumble, and chipcutter (since they don’t share the gold-orange mane color)

So, we’re going to assume that Derpy is the mother of every gray foal in Ponyville?