What do you mean, little brother?

Generally, at my sister's wedding, my brother-in-law is called my brother-in-law to show kindness and respect. Some rural customs also call him brother-in-law, which means my wife's brother. This is simple and clear, and it is also the name that most people are used to. I wonder if that's what your village calls it. In short, this brother-in-law is generally valued at weddings. What does the general brother-in-law want from him?