My surname is Shen, my ancestral home is Wulajie Town, Jilin City, and I still have a family tree. I don't know what the Manchu surname is. Which flag does it belong to?

Du Shan's surname (developed from Tudan in the jurchen era and later divided into Du surname and Shen surname), see Jinzhou Manchu surname.

Shen Jiashi (Shen Jiashi-there is no Shen Jia in the Manchu genealogy of Baqi, only Shen Jiashi, who lived in Wula for generations). This surname is the old surname of Jurchen. In the Jin Dynasty, the surname of Jurchen was Shen Gu, which is a transliteration of Jurchen pronunciation.

The Sheng family lived in Seqin for generations, and later generations also used Shen's surname.

Yan Ji's Richter scale (see Manchu in Beijing after the Revolution of 1911-Yan Ji changed his surname to Yan Heshen after the Richter scale)

Zhengbaiqi's surname is Shen, the old surname is Tudan, and the old surname is Aisingiorro with yellow flag. As for other flags, they were still Shen because there were already the Eight Banners Han Army at that time, and some Manchu people were captured by the South Korean Shen. They later joined the Manchu, but they were still Shen.

As for which flag it belongs to, you can't see it, and it can't help you analyze it.