I think they did Posey a bit of a disservice here: this is a character from all the way back in Generation 1 which inspired the creation of Fluttershy for Generation 4 and here she's just serving the story because somepony needed to create a bit of conflict and while earth ponies not having any magic of their own leading to jealousy certainly had a lot of potential, the script here really didn't give us much of a reason to care about what happens.

Special thanks to everyone who helped make this possible

I don't own any of the rights to My Little Pony.  My Little Pony is owned by Hasbro