Lilly was giving birth James was outside in the waiting room with Sirius and Remus. Lilly gave birth to Harry as she smiled the nurse took the after birth or what looked like the afterbirth to the trashcan. But then all the sudden there was a cry from the nurses arms. The nurse froze and looked down. The afterbirth wasn't after birth it was a baby. Lilly had twins the nurse quickly turned around to give the baby to Lilly.
But it was to late Lilly thought she only had a boy and Lilly was smiling. The nurse couldn't bring herself to give Lilly the second baby and the nurse looked down at the little girl.
" It's ok little one you'll be safe." The nurse says walking away from Lilly and the nurse smiled at the baby girl
Three months later
Lilly and James Potter were killed by Voldemort. Harry became the boy who lived while his twin sister that no one knew about lived to be a normal witch in a loving witch family. The nurse that took her gave her to a pure blood family and Harry's twin became the second child of that family.
Her name was Janelle Rosemary Malfoy. Lucius and Narcissa adopted her when she was just a baby and Draco was a baby. So they could pass of as twins and no one would notice at all they they weren't related at all. Narcissa was happy to have a son and a daughter so was Lucius.
As the years went by Draco was very protective over Janelle he kept her out of trouble and kept her away from anyone who would dare hurt his baby sister.