Wait, I’m Impious.
 
…I’m drunk.

@Impious
 
Oh, that would be lulzy.
 
“Princess, what was your mother like?”
 
“…Which one?”

Poor Luna probably has to deal with both the sun and moon until Celestia gets her powers back.

That isn’t supposed to be crossed out. Oh, hyphens. Why you so silly?

She wouldn’t be hard to identify. It’s probably a pony’s prerogative to take their child if she is one of the sisters reborn back to Canterlot. I’m sure they stay with their mortal family for a few years, though.
 
I doubt it happens often, since the sisters are pretty much the strongest beings around, with a few exceptions.
 
Kind of an interesting headcanon. Kind of gives their concept of family an odd twist, though. Celestia and Luna are family, but how do they feel about the mortals who give birth to and raise them in the event that their bodies are destroyed? Are they family too, or just particularly loyal subjects? Hmm.

Impious:
 
It’s a funny thought that they’d have to go find the new princess, kinda like people do with the Dalai Lama.

The Royal Sisters are immortal, but their bodies are not. If killed, they reincarnate, but as foals. Those stairs came out of NOWHERE.
 
For once, Luna gets to be the big sister.