Carlisle's fake mate

Edward and his sister Celia was turned by Carlisle, but both from different reasons. Celia is Carlisle's mate and he was already going to turn her, but Celia and her mother asked for Edward to be turned. Now fast forward to forks, Celia poses as a older sister to Edward Cullen though it is weird to act older to her own twin she does it to keep her husband and family acting human. What happens when Edward meets his blood singer? How will things end? And what happens when Celia finds out that Carlisle has been lying to her this entire time and Edward knew? (Esme doesn't exist)