Who is Xie Na’s father?

The "yaoda" that Xie Na refers to refers to her brother-in-law, who is the youngest brother among her father's brothers.

Yaba is the name given to the brother-in-law, that is, the youngest brother of his father. In some dialects, especially in Southwest Mandarin, "庺" means "the smallest one" or "the last one". For example, "yaozhimu" means "little finger", and "yaoji" in mahjong refers to one finger.

Yaoer or Yaonv is the youngest son or daughter, and by analogy there are Yao Ma, Yao Ye, Yao Po, etc.

Extended information:

Southwestern Mandarin is a Mandarin dialect gradually formed due to immigrants to the Southwest starting from the Ming Dynasty. Immigration is the main factor in the formation of Southwest Mandarin. It is generally believed that Southwest Mandarin is an extension of Jianghuai Mandarin. The two are related in origin and belong to the southern Mandarin dialect. However, academic circles are cautious about this statement.

Sichuan is one of the earliest areas where the Han people immigrated to the southwest. Sichuan was the land of Bashu in ancient times, with fertile land and relatively peaceful geography. The Han people first moved here after the Qin Dynasty unified Bashu (about 301 BC).

From Qin to Song dynasties, Han people moved into Sichuan to avoid wars and natural disasters. Such as the Huangchao uprising in the late Tang Dynasty. The main route for the Han people to migrate into Sichuan was across the Qinling Mountains, so the main immigrants were Han people from the Central Plains (mainly Gansu and Shaanxi). The dialect of the southwest at that time was mainly northern Mandarin.

Baidu Encyclopedia—Southwestern Mandarin

Baidu Encyclopedia—Yaba