What do you mean by six parents?

The eight characters and six relatives refer to grandparents, parents, sisters, sons of wives and brothers, sons of mothers and sons of daughters.

According to Records of the Historian and Biography of Yan Guan, "the degree of service is solid for six relatives." Tang Zhangshou's righteousness: "Six relatives refer to grandparents one, parents two, sisters three, sons of wives and brothers four, sons of obedient mothers five and sons of daughters six." Also refers to relatives, relatives, etc.