Mako and Bolin's Long Lost Sister

What if Mako and Bolin had a sister. What if their sister was Bolin's twin. Her name is Mi Yu and she is a fire bender who mastered lightning and fire, she also resembles Mako for she has jet black hair and Amber eyes. What if when Mako and Bolin's parents were killed she was killed. Or so they thought. What if she escaped her burning house and fled to Republic City? What if she met some friends named Kaya who's a water bender and Kikki who's an earth bender. Together they got jobs, an apartment and entered together as a team as pro-benders. They entered at age 14 and went all over the world winning pro-bending matches. When they move back to Republic City everything will change....