I recommend an ancient novel. The female protagonist is adopted by the male protagonist's family, while the male protagonist is the female protagonist's elder brother. In addition, the male protagonist has two younger brothers in his family. I have read this book a long time ago, but I have forgotten its name.

According to the information given, I recommend the book "The Farmer's Daughter" to you. The female protagonist transmigrated into a farmer's daughter. Her family only has sick grandparents and two little brothers. The male protagonist was a handsome and rich fiancé, while the female protagonist shouldered the burden of making a living for the family. She accidentally became well-off. In this novel, the male protagonist was the fiancé of the female protagonist, so he was adopted by the female protagonist's family. The male protagonist had two younger brothers at home, which matched the plot in the question. I hope you like this fairy's recommendation. Muah ~😗