After a Marriage Swap, My Officer Brother-in-Law Spoils Me Rotten

(A heads-up: there is a plotline involving adopting an orphan and becoming their stepmother. If that's not your thing, please skip this one!) Ji Xing spent her whole life with Zhang Jingyuan. They went from having nothing and living in a cowshed to her becoming the wife of a technology expert. They had a son and a daughter, and it took them thirty years to build that life. At forty-eight, who wouldn't say Ji Xing was lucky? She had chosen the right man when she was young; they were loving, her relationship with her mother-in-law was harmonious, and her children were filial. That is, until Ji Xing was diagnosed with terminal bone cancer. Her supposedly loving husband cut his finger in front of her hospital bed and forced her to sign medical instructions written by who knows whom. Her supposedly filial children immediately signed a form refusing further treatment. And her seemingly harmonious mother-in-law leaned on her cane and ordered people to dump her in a rental apartment. Ji Xing was exhausted... On her deathbed, she thought that if she got another life, she would stay far away from those parasites. But when she opened her eyes again, her green-tea stepsister was insisting on marrying Zhang Jingyuan, that gold-digging pretty boy. Fine, fine! As the eldest legitimate daughter of the family, Ji Xing would make sure her wish came true! A marriage swap was one thing, but what was the younger sister's fiancé, whom Ji Xing had met only twice in her previous life, like now?