移民局网站是说，有四种方法，前3种是教会受洗证明、学校记录、普查记录，第四种我觉得你可以考虑：
Form I-130 Instructions 12/18/12 Y Page 4
Form I-130 Instructions 12/18/12 Y Page 4
In such a situation, submit a statement from the appropriate
civil authority certifying that the document or documents are
not available. You must also submit secondary evidence,
including:
What If a Document Is Not Available?
D. Affidavits:
Written statements sworn to or affirmed by
two persons who were living at the time and who have
personal knowledge of the event you are trying to
prove. For example, the date and place of birth,
marriage or death. The person making the affidavit
does not have to be a U.S. citizen. Each affidavit
should contain the following information regarding the
person making the affidavit: his or her full name,
address, date and place of birth, and his or her
relationship to you, if any, full information concerning
the event, and complete details explaining how the
person acquired knowledge of the event
