After a horrible accident as a filly, Lily became blind and deaf. After their parents died, Roseluck and Daisy refused to give their sister up to an adult foster care and took her into their care. It's a long hard road but they wouldn't have it any other way.

(Minor inspiration taken from this story https://www.fimfiction.net/story/508828/unseen-unheard. Go give it a read, it's amazing and I love it a lot. I think you all will to. Just wish I thought of it first😂.)