The Gold-Digging Foster Sister of a Down-and-Out Crown Prince

[Living together before falling in love + unrelated step-siblings + devoted and wholesome romance] After transmigrating, Yu He becomes the gold-digging stepsister who abandoned the male lead when he was down on his luck. In the original novel, Feng Jin is the fake young master who was switched at birth and raised by a wealthy family. When the real young master returns, Feng Jin is cast out and becomes a poor young man working three jobs a day. His stepsister, once his closest companion, immediately turns on him too. She cuts ties with him and fawns over the real young master, calling him “big brother.” Later, the wealthy family's real daughter is found, and the original owner is kicked out as well. With nowhere else to turn, she goes back to Feng Jin and pesters him to support her, only to start insulting him again a few days later. It isn't until Feng Jin is reclaimed by an elite family that the original owner regrets her actions. When Feng Jin sees his gold-digging stepsister crawling back as soon as his fortunes change, he can't stand her. He turns around and sends her off to a remote mountain village to raise pigs. Yu He, who has transmigrated into her, nearly faints. She tries acting sweet and obedient to rekindle what little sibling affection the male lead has left for her. Yu He: “Big brother, are you tired from work? Let me massage your shoulders.” The male lead transfers her money without changing expression. “If you want money, just say so. You don't have to do this.” Yu He: “Big brother, you've been hurt. Let me put some medicine on it.” The male lead transfers her money again. Yu He is puzzled. Didn't he say he hated gold-diggers? So why does he keep sending her money? In the end, Yu He brings a rich second-generation heir to the male lead. “Big brother, this is my boyfriend. He says he'll support me from now on.” The male lead's expression changes at once. He puts a black card in her hand and forcefully kisses her. “I'm richer than he is. I'm the only one who deserves to support you.” Yu He is stunned. When did their sibling affection turn into something else? And when did he find out that he was incredibly rich?