I’d like to think Shining recently broke his legs and was bed-bound for some time so Velvet put him in diapers appropriate to his size to make caring after him and twilight at the same time easier. There were a bunch leftover after he healed and were tossed into the changing table and forgotten. Shining still being magicless would mean he’d lack the dexterity to be able to put a diaper on himself while making sure the diaper is sufficiently snug, nor putting on foal powder to avoid getting sweaty and waking up throughout the night.  
So really what happens next is Velvet lifting him onto the changing table.

now that I think about it, Velvet seems to have an amused look on her face.

Those are his size though, let’s look into that.

@Twilight_Shimmer  
Then your guess is 100% on the spot, if Twily refuses potty training then Shiny will have to stay in diapers untill he moves out from home, but if Twily refuses to potty trained then she will have at the age of 6 which is 2000 days from the moment this picture is shown, she will have all of her books taken away & won’t be allowed to go enter Celestias School For Gifted Unicorns.

@Background Pony #2FE6  
One of em at least XD

@Twilight_Shimmer  
Is that your guess?

@Background Pony #2FE6  
If twily refuses training and stays in diapers, thus shall shiny also have too?

@Twilight_Shimmer  
Accidents can always happen, better safe than sorry i say.
 
Well i will let you take a guess and i will give 3 chances.

@Background Pony #2FE6  
I doubt that would happen lol. :)
 
Also wonder what would happen if Twily refused potty training XD

@Twilight_Shimmer  
Yeah i know but i am afraid that Shining will hurt Twily, you know if he roled over & such.

Twilight Velvet: Starts Diapering Up Shining Armor

@Background Pony #2FE6  
No i mean Shining getting into Twilys crib and laying down besides his sister and taking a nap next to her

@Twilight_Shimmer  
Nah, Twily has her own crib.

@Background Pony #2FE6  
hmmm I dunno, I could see many things happening good or bad (depending on one’s point of view) Maybe taking a nap with Twily in her crib even :)

@Twilight_Shimmer  
I felt that Twililight Velvet should make a clear point to Shining Armor that theft & lying isn’t ok & is a very serious matter & that she need to punish him, yet not go to harsh on him with that the punishment will only be in efect when they are in private & that it is only the diaper punishment that counts for now, but that Twilight Velvet needs that threat of that things could change & take a turn for a lot worse if he misbehaves. Still it will be a long time before he is out of diapers, little Twily here will take about 1000+ days to get fully potty trained, she is almost a newborn foal in this picture, so that is a 1000+ days for Shining Armor to be in diapers, needless to say Shining Armor has a long time before he isn’t changed by his Mommy or Daddy again & i think that he will have to be re-potty trained when the punishment is over, wonder if he becomes a DL after this & wonder if he can behave & not be punished futher by his Mommy & Daddy. What do you think will happen with Shining Armor?

@Background Pony #2FE6  
cute! :)

@Twilight_Shimmer
 
Changes has been made here so i hope you will like them.

Shining Armor: N-nothing!
 
Twilight Velvet: Sigh, if you so wanted to try out your Sisters’s diapers you just could have asked me.
 
Shining Armor: R-really!
 
Twilight Velvet: Yes sweetie really, i understand that you are jellous, with so much of mine & your father’s attention being given to little Twily lately & that you felt left out.
 
Shining Armor: Thank you so much Mommy, i love you!
 
Twilight Velvet: I love you too sweetie, how ever it is NOT! ok to steal & lie to you Mommy & for that you need to be punished.
 
Shining Armor: W-what! n-no spankings please!
 
Twilight Velvet: Calm down sweetie i won’t spank you.
 
Shining Armor: Y-you won’t?
 
Twilight Velvet: He he no, but for the crime of diaper theft your punishment will be this, you shall from this day to the day little Twily is fully potty trained be put back into diapers all of the time when you are home.
 
Shining Armor: W-what!
 
Twilight Velvet: Yes &! fo lying to me like you did, you will be banned from using the bathrooms when you are at home, you will use your diapers for making pee pee, and poo poos for Mommy & Daddy just like little Twily does & ask either me or your father to change you when you have used them.
 
Shining Armor: N-no it isn’t fair.
 
Twilight Velvet: If we find out that you are trying to taking of your diapers you the next punishment me & daddy will start to treat you the same way as little Twily, like a little filly foal, with you being feed with a baby bottle by me & daddy, having a pink pacifier in you mouth, being carried around in a big baby stroller sleeping in a crib, going back to day care, be dressed in pink dresses, pink bows & all of your big colt things will be thrown away.
 
Shining Armor: Y-you can’t be serious?
 
Twilight Velvet: Oh i am very serious alright, now jump up on the changing table & let’s get your flanks all diaperd up shall we.
 
Shining Armor: I-i won’t do it!
 
Twilight Velvet: Now now Shining if you don’t obey now, i will make you wear your diaper 24/7 in public, in school & during the time that you are with you friends.
 
Shining Armor: Y-you can’t!
 
Twilight Velvet: Oh i can alright.
 
Shining Armor: F-fine i will do it.
 
Twilight Velvet: What a good little colt, now jump up here sweetie & let’s get started, pat pat.
 
Shining Armor: GULP!

@Background Pony #2FE6  
id change the nr’s to something like “you will use your diaper for making pee pee, and poo poos for mommy just like Twily does.” The Nr’s just does not seem to flow quite well. :) still its a cute lil story and Shining’s lucky

Quick! Use the ‘I was gonna use the stuff inside the diaper to do experiments with’ -excuse!

rip