I have two novels that I can recommend to you. They are "The adopted sister is the Demon Cult Master" and "After being adopted, she became the treasure of the five big shots." Both of them involve the plot of an older brother adopting a younger sister. The main characters of the former were An Lingyun and Zhuo Yang, while the main characters of the latter were Jian Yuqi and the five big shots of the Xu family. I hope you like this fairy's recommendation. Muah ~😗