By the way,

来源: 于 2011-04-25 21:21:18 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

Your mother has to be a US citizen formally (get the certificate), then your brother can get the married later. Otherwise, the F2B I-130 will be void and can not be upgraded to F3.