我想邀请哥哥，嫂子和侄女来美国玩，哥哥因为忙，可能来不了，所以也就嫂子带着侄女暑假时来一个月。我不太清楚他们签证需要准备些什么材料，
需要我和我哥哥的兄妹公证
-They had better have this document for the visa applications..
以及他们的父女母女公证吗？
-Your brother marriage certificate (original) and the child birth certificate (original) and not need to 公证 these documents and not need to translate into English (the Visa officer know Chinese very well).
还需要一些其他的什么材料？
-See:
