it is almost right.but the brother哥哥that you have the wrong spelling.in my opinion,althong your brother has already got married.but they are still your family members.you can say that you own a big family,incuding your sister in law弟媳妇or嫂子and your nephew侄子。I think it will feel more close than what you said that you family members have become 4 and your brother have his own small happy family.
Do you agree with me?