We'll see in Season 4! (don't worry, a lot of people's headcanon will probably be crushed. Including mine. Boo hoo) And before you say it's in the wikia, let me say that the part about Rainbowshine is probably an educated guess.
According to interviews by Faust herself, after it was decided that they couldn't use the name Firefly for the character who would become Rainbow Dash, she instead went on to say that Firefly was, instead, Rainbow's mother. So this right here is pretty much canon.