I know that it says on one of the scripts early in season 1 that Sybil is 17 at the begining which is 1912 which would make her birth year 1895, but in season 2 episode 7 when Mary and Edith find Sybil and Branson in the inn Mary says Sybil is 21 and the time period then was 1919 after WW1. If that is true wouldn't her real birth year be 1898?