回复：回复：急问皮匠等:给父母办绿卡,他们的结婚证丢了,怎么办结婚公证

From what I know, if your notarized birth certificate has both your dad and your mom's names on it, they don't need the notarized marriage certificate.
-It is true. Because even if your parents can not prove their marrige, but you can prove they are truely your parents. So no matter whether they are still in marrige or not, both of them are qualifed for the green card application under your sponsor.