My sister's name is Mo Yan, but how does my brother get a name?

My sister's name is Mo Yan, and my brother's name is Mo Yu. My sister's name is Mo Yan, which is simple and pleasant to listen to. If you want to echo this name, you must name it Mo Yu. Mo is a surname, regardless of it. My sister's name is Yan, and there are many corresponding words, and the most pleasant and understandable word after combining with the surname is Yu Zi, so my sister's name is Mo Yan and my brother's name is Mo Yu.