Sun Quan made his father emperor because he was his father's son and his younger brother Sun Ce was his father's son. Then his father had only two sons, and Sun Ce died, and then no one argued with him. If his younger brother Sun Ce is made emperor, Sun Ce will have a son. If Sun Ce is made emperor, his brother's son will compete with his own son for the throne.

So like this, Sun Quan only thinks about the throne of his children for his own throne, and he just named his younger brother Sun Ce as the eternal king of Changsha. After all, if you think about it, he just made a posthumous title for his father and his brother just made a posthumous title. If his brother has no children and no descendants, I believe Sun Sun Ce actually doesn't mind making his brother emperor, but the most important thing is that his brother Sun Ce has children. If Sun Ce did this, the situation in Wu would certainly be affected.

So if Sun Ce didn't have children, he would definitely be made emperor, but because of Sun Ce's embarrassing political status at that time, he made Sun Ce king.

The reason why Sun Quan didn't establish an emperor for his younger brother was mainly to consider the rationality of children inheriting the throne in the future. If Sun Ce becomes emperor, Sun Ce's children will have the right of inheritance, which is a threat to his children's right of inheritance.