Li Chengqian's younger brother was Li Zhi. Li Chengqian was the eldest son of Emperor Taizong of the Tang Dynasty. He was made the crown prince, but was eventually deposed and exiled to Qianzhou. Li Zhi became the crown prince. The search results did not provide more information about their specific relationship and interaction.
Yes, according to the information provided, Li Chengqian was Li Zhi's biological brother. They were the sons of Emperor Taizong and Empress Zhangsun. Li Chengqian was once conferred the title of Crown Prince, but was demoted to a commoner because of his rebellion. In the end, Li Zhi became the Crown Prince and ascended the throne as Emperor Gaozong of Tang Dynasty.
Li Weiyang's younger brother was considered a fool because he suffered from a rare congenital disease that caused his brain to develop abnormally. This disease had not been completely cured in the medical world, so Li Weiyang's younger brother needed long-term treatment and rehabilitation training. In order to protect her younger brother, Li Weiyang had taken various measures, including seeking the help of doctors and experts inside and outside the family, as well as spending a lot of time and energy to train her younger brother. Although her efforts did not seem to have much effect, Li Weiyang had always believed in her ability and determination to create a better future for her brother.
Li Chengqian had a total of three sons, namely Li Xiang, Li Jue, and Li Yi. Li Xiang had held many positions in the Tang Dynasty, including Huaizhou and Ezhou. Li Jue was the grandson of Li Shimin, Emperor Taizong of the Tang Dynasty. He once served as the governor of Ezhou and was posthumously awarded the title of envoy to Qingzhou's military, Qingzhou governor and Zong Zhengqing. As for the relevant information about Doctor Li, there was no relevant information at the moment.
Li Chengqian's ending in the play "Celebrating Years" was to be deposed as a commoner and exiled to Qianzhou. In 644, he died in exile. Emperor Taizong of the Tang Dynasty stopped court for him for several days and buried him according to the etiquette of the Duke of the State. This was his ending in the movie.