Twilight and Maude actually had an enemies to lovers relationship which is very wild. In this AU Twilight was an Author for a book of magical essays which briefly touched on gemstone magic. After publishing her works, some random small town author sent in a bunch of critiques on her knowledge of Gemstone magic, and several essays on why Limestone did not have the same magical properties as any old rock thank you very much-
The two sent each other petty, passive aggressive emails about why You Are The Wrong One Actually until they accidentally met. Pinkie was simply introducing Twilight to her dear old sis, and when the topic of what she did for work came up….
Well it was awkward to say the least. However, the two began to spend more time with each other, slowly beginning to become friends.
Like, five years later they finally got together and had kids eventually but it was a long process.

Amity is the older sibling, being two years older than their sister. They are a hopeless romantic and optimist, with a interest in terrible TV and basketball. They did try to get into rocks for Maude, but it didn't really interest them the same way team sports seemed to. They ended up being a gym teacher and playing on the local basketball team :)
Monzonite is a nervous thing, and despite being the younger sibling is much taller than Amity. Monzonite gets very invested in their interests, and often formed small obsessions with different subject over their childhood. She is very interested in rock classifications, which Twilight totally called because no way was Maude not going to infect one of their kids with Rock Mania.