Renesmee Cullen Twin Sister Sasha

Renesmee has a twin sister Sasha. Sasha was a suprise to the whole family. She is more vampire than Renesmee. So she grows faster than Renesmee. She has the power to levitate things, she also can make ice come out of her hands. No one knows about her powers beside, Emmett, Alice and Seth. (And Renesmee) The rest of the family don't pay much attention to her, like she not there. Though she till loves her sister. When the Volturi come to kill them. The family use Sasha a a wepon. Cause she looks older than Nessie. Does everyone find out about her powers? Will the Volturi want her? Will she join? Will Alec fall for her?