The seniority is generally determined by a few words by the elders or the most prestigious people in the clan.
These words often have special meanings, or are read continuously. It will form a sentence, or represent some characteristics of the clan, etc.
Usually it is a group of 4 words, and then write 8 or 16 words,
Every word is a generation. After you use it, you have to continue writing.
But many people don’t care about these now.
The words on the family tree are reincarnations. Anyone with a family tree knows this. Taking the surname Zhang as an example, I know that there is a family whose middle character is "Everything is prosperous in the Qing Dynasty". It was passed down from an ancestor. (I think this ancestor should have determined these five characters during the Qing Dynasty.) The generation with the character "big" will be the next generation with the character "qing". The next generation of the character "Xing" is "大", and so on. If you are older, I guess you have always lived in the same area. Although you don't know each other, you generally know each other. If an ancestor spreads his branches and leaves, his descendants will be distributed all over the country. Several years later, when the descendants met again, although they were still sorted according to the family tree, it was impossible to tell which person had the greater backup. Maybe some people have the next generation when they are 20 years old, while some people have the next generation when they are 40 years old. This is a generation difference. The seniority according to the family tree is cyclical. This results in people who may all be of the "big" generation, but are separated by a cycle. I don’t know if you understand this. If you want to know exactly which generation you are from.
You can only look up the family tree. The direct lineage is recorded, such as the number of generations, etc. It is inaccurate to rely solely on the characters in the middle of the name