(Warning: Baoyu and Daiyu will not end up together, but Jia Mu, Jia Baoyu, and Xue Baochai are not portrayed as villains. The story takes an objective view rather than painting everything in black and white. There's a spatial dimension, and Daiyu will enter it later.)
The bad news: Miao Zhen, a food blogger, has transmigrated!
The good news: She's become a princess of the current dynasty!
The even worse news: As soon as she arrives, she's told the emperor has arranged her marriage to a widower in his forties!
Wait... You're saying this widower lives in Yangzhou and is named Lin Ruhai?
Not long after she marries him, her imperial brother becomes emperor and her mother becomes empress dowager? She's been made a Grand Princess?
As the saying goes, an emperor's guilt is enough to let someone live comfortably for the rest of her life. And this emperor is her own brother!
With compensation from both the emperor and the empress dowager, she raises Daiyu and wields great power. (The heroine stands on her own, and Lin Ruhai will still die.)