Magnaminity is the youngest daughter of Fluttershy and Discord. She appears in Ghosting and Glorified. See stories below:

https://www.fimfiction.net/bookshelf/1294304/bright-future?order=latest

I didn't do it on purpose, but Maggy here really reminds me of that picture of the girl smiling in front of the burning house, and to be honest, that captures her personality very well. She has uneven horns, a single large fang that doesn't fit in her mouth, and is the sole reason Flutterhsy never had anymore kids. She kinda broke some things on the way out. She's a bony little coil pony dragon bat with mischievous ferret energy. If Amity is the noble daughter of Discord, and Fallacy is the good son of Fluttershy, Maggy is the bad daughter of them both. Cruelty, sarcasm and wit masked by a sweet, giggly demeanor offering a hoof shake with a knife hidden behind her back. A majority of her body's muscles are actually in her tail, and she uses it to snake around and hold onto things. She's so flexible that some wonder if she has bones in there at all, despite being fairly thin. Naturally, she's Cheesette's best friend.