After I Transmigrated, I Became a Substitute?

Novel blurb: The Duke of Cui, who keeps his distance from women, brought a peerlessly beautiful woman back from Hongdu, leaving the people of Youzhou City full of speculation. At first, Cui Yuan said, "If all you want is to be a good daughter and little sister, you'll have a life of wealth and comfort, free from worry." Bai Mei, who had come from the apocalypse, nodded emphatically! As long as there's food, I'm good! Later, Cui Yuan said, "How about you become my wife?" Bai Mei gazed at Cui Yuan's impossibly handsome face and thought that going from a substitute little sister to an empress didn't sound so bad. An extraordinarily beautiful, lazy woman x a refined hypocrite P.S. This is a fictional setting. Historical purists, please stay away. There won't be much space travel, either. New novel currently updating: Quick Transmigration: Tough as Nails, Few Words Man Xing's mission is to become a winner in life! Grind the original male and female leads into the dirt! Please note before reading: 1. No seduction, no flirting, and no getting together with the original male lead. 2. Live out a whole lifetime in each world. 3. Some mission worlds occasionally have couples, though most are weaker than the protagonist. 4. The protagonist grows over time and prefers to keep a low profile while building up her strength. Theme: