This article is from the FAQ, by with numerous contributions by others.
Once the application step is begun, is it TRUE that parents must
remain where they are at? Does this apply to third countries like
Venezuela? I am petitioning for my parents and they are in Venezuela.
So they can't leave Venezuela?
They are not required to remain where they are. They can go anywhere
they please. But because they would have applied for an immigrant
status, it may be difficult for them to come to U.S. on a nonimmigrant
visa such a as Tourist visa.
Q 2.Is there a distinction between petition form and
application form? For immediate relative case, is the
I-130 the petition and application form or is it just
the petition form?
Same thing. File Form I-130.
Q 3.For immediate relatives, is it really required to produce
birth certificates of the parents? (I am US citizen and
have my birth certificate, but they are Indian and don't have
birth certificates)
Pick up the affidavits of birth from our FAQ (http://www.immigration.com).
INS may require additional official proof that birth certificates
are not available (e.g., letter from office of records, or
local municipality).
 
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