What is the relationship between winning Fu Su and winning Ziying?

Logically speaking, the biggest possibility is Gao's son, Qin Shihuang's younger brother, Qin Shihuang's nephew, and cousins of Fu Su and Hu Hai. First of all, Wang Xiang of Qinzhuang has two sons, one is Qin Shihuang Ying Zheng, and the other is Qin Shihuang's younger brother Gao, so the possibility that Zi Ying is Qin Shihuang's younger brother is ruled out. Because Zhao Gao and Hu Hai killed the sons of Qin Shihuang, if Zi Ying is the son of Qin Shihuang, there is no reason to let Zi Ying go, so the possibility that Zi Ying is the son of Qin Shihuang is ruled out. If Zi Ying is the grandson of Qin Shihuang, then Zi Ying's son, the great-grandson of Qin Shihuang, can conspire with Zi Ying to exclude Zhao Gao three years after Qin Shihuang's death, that is, at the age of 52. This is obviously wrong, so the possibility that Zi Ying is the grandson of Qin Shihuang is ruled out. But Zhao Gao elected Zi Ying as the king of Qin, and Zi Ying must have something to do with Qin Shihuang. Therefore, it is only possible to think that Zi Ying is the nephew of Qin Shihuang, and all the impossibilities are ruled out.