Wang Dao
While Sima Rui served as Left Prime Minister under Emperor Min, the teenage Sima Shao was put in charge of defending Guangling. After Sima Rui declared himself the Prince of Jin following Emperor Min's capture by Han Zhao in 316, he initially wanted to make Sima Pou his crown prince, but after Wang Dao pointed out that traditionally the older son should succeed him, he created Sima Shao crown prince. Sima Shao remained in that status after his father declared himself emperor (as Emperor Yuan) in 318, after Han Zhao executed Emperor Min.