In Chaoshan area, my sister is getting married. Why can't my unmarried brother appear?

This should be a bad local custom. Why can't an unmarried brother show up? In many places, people will carry their sisters to their in-laws' homes, and even send them to their in-laws' homes all the time to see them off. Who knows why they have such bad habits locally? It's really wrong to engage in such bad habits at this age. Does my brother have to get married before my sister? They must think that my brother is not married yet, and my sister is married first. It seems that their parents are very bad and have no face.