A Handbook for an Empress's Rise

She transmigrates into the body of a poor girl whose father doesn't care for her and whose mother doesn't love her. Just as she's about to be sold to a butcher as his second wife, a messenger from the Duke's estate arrives, claiming she's their long-lost eldest legitimate daughter. There's also a fake heiress in the family, adopted years ago. Zheng Qingshu is just about to roll up her sleeves and fight the fake heiress for three hundred rounds when she discovers she's become the emperor's full sister and a princess, blessed with the innate strength of the founding emperor himself. Since she's already so close to the throne, she might as well do it the honor of taking a seat.