Not by law - 回複：今天媽媽綠卡麵試總結－－注意父母綠卡不能由子女做翻譯了

父母綠卡不能由子女做翻譯 - This is not required by law, otherwise VO would not let you to be the interpreter.

The problem is caused by a few VOs who are not clear on the policy of USCIS on the issue. - Interpreter