How are sibling relationships determined? In order of worship?

Generally the order of initiation. The Chinese tradition is to rank them according to seniority, so the one who enters first is the senior brother, and the one who enters later is the junior brother.

But there are also special, such as the "Dragon Eight" in the Xingjiu faction, the general eldest brother is the ability to be, who is good at kung fu, who will be the eldest brother, the other brothers according to kung fu theory a ranking, in order to rank down.

In short, the rules are made by people, each industry sect has different standards.