In ancient China, it was common for the same person to marry a sister, but they usually had to meet certain special conditions. Under normal circumstances, if the sisters came from different families, they had to be ranked according to a strict seniority system to ensure order and harmony within the family. In ancient society, family and social status were very important factors, so it was also very important for people of the same generation to distinguish each other's identity and status. In this case, certain rituals and symbols would usually be used to distinguish them, such as using different garlands, jewelry, or clothing. If the sisters were the same person and there was no strict seniority system in ancient society, they might be treated as brothers or father and son when they married. In this case, the seniority of the married sister should be determined according to the family of the wife, usually according to age or status. For example, if the younger sister was married, her seniority would be lower than the older sister. However, if the older sister had passed away or was too old, one could consider using the older sister's seniority as the younger sister's seniority.