Mitch and his Sister?

This is not a Scomiche story (I know right?) This is A story about Mitch's Sister (Im going to use my name cause i'm not creative) Addie. Addie is four years younger than Mitch. People think that Addie and Mitch are twins because Addie is a bit taller than Mitch and they are almost Identical. Mitch and Addie were separated when Addie was 3 and Mitch was almost 7. Mitch found about Addie when his Mom shows up at one of the Pentatonix shows with Addie and tells them they are related. Mitch kept it to himself for almost a year. Scott finds out when he checks Mitch's Phone, Mitch tries and covers it up but Scott stops him and tells him it okay and then asks where Addie is, Mitch says she is a few block away... Find out what else happens in the book.