I have few questions to ask you about my parents’ green card applications.
1. I just took the oath on
-Not yet. You need to get the US citizenship certificate and provide the copy of it for the I-130 filing.
2. My parents came to the
-No. They do not need to extend their B2 status no matter they will apply for the green card before or after their I-94 expires.
3. Is my parents’ marriage certificates the part of necessary documents for applying green cards?
-I think it is need for your father's green card application base don the I-130 Instructions, not your mother's. So, had better prepare it.
4. Do I have to submit the original of my birth certificate, my parents’ birth certificates and their marriage certificate or the copies are fine?
-The photocopies of these documents are good enough.
