@Background Pony #30EB  
Why does no one pay attention. It has always depended on the family.

Wait, ponies doesn’t have surnames. I thought that was true. That ponies didn’t had surnames. I mean, literally… Forget it, I really don’t wanna say it out loud about why ponies have surnames, but I’m afraid…

[@furrypony  
The only pony naming rules seem to be that  

The only pony naming rules seem to be that  

Wow, this chat has devolved into a cesspool of AIDS
 
OP is master troll. Praise be!

@JetstreamGW  
And I’ll note, their mom ISN’T a Pie  
That fits neatly into the fanon of Cloudy Quartz being Iggy’s second wife, with Surprise Pie’s current fate unknown.

@JetstreamGW  
Fitting into the part of my earlier summarized headcanon about Earth pony clan-based naming conventions, I further headcanon that the modern Pie family is a combination through marriage of (at least) two clans, one from which the Pie name is derived, the other the traditional rock farmers. The former is at least prominent enough to have a lingering surname while the latter (iffy headcanon here) uses the choosing stone as a pretext to gain prominence by forming marriage alliances with minor clans specializing in different minerals, the most recent being quartz.(end of iffy headcanon.) At some point, somepony loved a Pie and two unrelated specialties combined into one family, Pinkie being our best hint at what the pre-rock farming Pies were like. Side note: I think her ancestor may have invented the pie throwing gag in Equestria, thus ingraining the Pie bloodline with opportunities in comedy and parties. Either that or they also combined with minor clans with those specialties.

@TexasUberAlles  
Fair enough, forgot the Pies. They’re an aberration though. And I’ll note, their mom ISN’T a Pie.

@Stotter  
[Realized I didn’t headcanon the naming conventions of the other two tribes, so here I go]  
Pegasi may well have invented nicknames in this world because their names work in a similar manner: Their names either describe the individual metaphorically or based on character traits, like Hurricane and Pansy, as opposed to Earth pony clans based on specialty, like Smart Cookie and Puddinghead. The Shy family seems to have found a way to blend both of these together, perhaps by coincidence, both being shy by nature and inspired to include that in their first born’s name, but they didn’t start a clan around it, because why cultivate shyness on purpose?
 
Finally unicorns, who focused less on naming conventions because they were more concerned with titles. To them, it didn’t matter what you were called at birth, because either you were a noble born with a title, or you had to earn a descriptive title by becoming a wizard. Otherwise, you were the servant class of unicorn.
 
Modern day ponies who don’t fit these conventions can be explained as the result of over a millennium of harmony mixing their cultures together, making for many mold-breaking opportunities.

What if different tribes of ponies had different naming conventions and at some point it was decided that anypony could use any naming convention they wanted to. It seems that only established clans that emphasize tradition even use them anyway, even then there’s the choice of using family name or theme naming based on family business, a choice every parent makes independently. The Pie, Apple, and Rich families have been shown to do both. The next generation of Cakes could give names based on cakes without using the word “cake” if they wanted. I headcanon there’s a Milk family and she took his family name either because the Rich family is more prominent in society or it’s just a gender thing like irl.

@Amber  
I’ll just say this: when Spoiled Rich next appears in the show she’ll be credited as Spoiled Rich, mark my words.

@JetstreamGW  
Not a single sibling has so far been shown to have a shared name with another member of their family  
Pinkie– in addition to having four sisters also named Pie– mentioned a Granny Pie in the Series Premiere and a Nana Pie in Too Many Pinkies. The Cakes also named their twins Cake.
 
My (completely unsupported, haters gonna hate) headcanon is that Carrot Cake isn’t a Cake, he’s a Carrot– brother of Golden Harvest and uncle of Carrot Top. Ponies obviously play fast and loose with family naming conventions.

I insist; they’re Burmese-like names.

@TexasUberAlles
 
 
“They are canonically called “The Apple Family” and “The Apples”
 
That’s correct, I never said otherwise.
 
 
“What’s the distinction, then?”
 
Having apple themed names and having “Apple” as surname are two different things.
 
Big McIntosh/Macintosh, Applejack, Braeburn and Red Gala are apple themed names, but that doesn’t mean they are named “Big Macintosh Apple” or “Red Gala Apple”, see what I mean?
 
Same with characters that are considered part of said family but don’t have an apple themed name, like Babs Seed. She’s not “Babs Seed Apple” because it’s not a surname.
 
Same with the “Pies”, Ingenous Rock and Cloudy Quartz are married but that doesn’t make Cloudy “Cloudy Quartz Rock, much less their daughters who are the actual ponies named after pies in that group.
 
On the other hand, we have Mr and Mrs Cake, but it was later revealed that was mostly on the happy coicidence about them having similar themed names rather than Cupcake taking Carrot’s second name.
 
 
@TexasUberAlles
 
“I mean in the show”
 
Wait, hold on. One thing is to consider the canonicity of the events in the show over the ones in the comics, for example, and another being picky and grasping at straws when it comes to those names.
 
Twilight’s parents names are Twilight Velvet and Nightlight. That shouldn’t even be argued. They are referred as such in other media and specially in the toys. Just because for some reason they don’t show it in the credits doesn’t make it any less canon.
 
 
Hasbro’s toy department might not breathe on the show staff’s necks, but we’ve witnessed that they do pay attention to these details. At least enough to mix some of the show names with the ones of the toys (Trixie Lulamoon), to adopt some names that came straight out of the fanbase (Steven Magnet) or to make writers backpedal on names in order to avoid copywright issues (Coco Pommel).
 
 
Also:
 
“Mr and Mrs Sparkle”
 
Kinda like “Mr and Mrs Shy”. It’s safe to assume this is just DHX being silly and those are just placeholders for their real names. I mean, Look at the Diamond Dogs, they were never credited with their names either and we would have never known them if someone hadn’t actually asked Faust about it.
 
For all we know, Fluttershy’s parents could have simply be named “Mom” and “Dad” in the script, which could mean they don’t even have actual names yet.
 
 
“Yes, it is. That’s clearly how they intended it to be perceived”
 
Then that would mean Filthy Rich and Spoiled Rich are one exception, not the rule, and it speaks more about the reasons (her own character’s reasons) to change her second name, since this is not something married couples do there.
 
“We know that pony naming convention isn’t absolute”
 
I can somewhat agree with this, but I will also invite you to check the list of pony names ever since G1 and you will find that there’s actually some kind of little system behind naming a pony and that’s something hasn’t changed even now in general.

@TexasUberAlles  
On the one hand, there’s the Rich, the Cakes, the Paleo and (apparently) the Sparkles. But also the Apples who make do with mostly apple-related names but collectivelly call themselves the Apple Family, just like how the Pies don’t all have Pie as a surname, but their very old line is also known as the Pie Family. It would seem, one can argue, that the ponies are at some early, transitional period where commoner families are adopting fixed family names for themselves. Just like how it happened real life. Perhaps the ponies would formally adopt family names one or two generations later.
 
/fanwank

That sometimes ponies change their names at marriage is confirmed, not that surnames are the norm.
 
Not a single sibling has so far been shown to have a shared name with another member of their family, and plenty of married couples don’t share a name. In fact, Filthy/Spoiled and Carrot/Cup are the only examples I can think of that DO share names.

@Amber  
That only means that most of Applejack’s family have apple themed names, not that they have surnames or that ‘‘Apple’’ is a surname  
What’s the distinction, then? They are canonically called “The Apple Family” and “The Apples”, this seems like a pretty moot point.

@Background Pony #74D4  
I mean in the show.

@Magma_ERuptiOn  
Yeah, until they got real names.

@Amber  
Yes, it is. That’s clearly how they intended it to be perceived.
 
We know that pony naming convention isn’t absolute but it does often apply with married couples, don’t forget Twilight’s parents were officially credited as Mr and Mrs Sparkle.

@Stotter
 
Cup Cake was always Cup Cake (or basically “Cupcake” since that’s what they were obviously going for) though. Marrying Carrot Cake was just a funny coincidence.
 
Like Babs Bunny and Buster Bunny “No relation” kind of case.

I wonder if Cup Cake was called something else? Cup Size is my favorite gag one, but Cup O’Sugar works best.

@Magma_ERuptiOn
 
“Milk is her maiden name”
 
No it’s not. That’s like saying “Sparkle” is Twilight’s maiden name when we know her whole family all have different names.
 
If we try to find the most rational explanation it could be that Spoiled just took her husband second name because she isn’t fond of her own, it was a writer’s slip-up or like I said before, it was just a Coco Pommel situation and just simply changed her name.
 
@TexasUberAlles
 
 
That only means that most of Applejack’s family have apple themed names, not that they have surnames or that “Apple” is a surname.
 
Just look at the Pie sisters, they have “Pie” in their names but both of their parents have rock themed ones.

There was literally an Apple Family reunion in the first ten minutes of the first episode.

@Amber  
Milk is her maiden name, because they weren’t married in the flashback.