My parents have valid multiple-entry visitor's visa for USA (till 2012) on old passports that were damaged due to flood. They have received new passports. Their old passports are slightly wrinkled and stained, though the visa pages are absolutely fine. All the information on the visa is clearly visible alongwith their photographs. I am settled in USA and my parents want to visit me next month.
My questions are as below:
1. Can my parents visit USA [on their new passports] with visa in their old passports? OR
2. Do they need to re-apply for visitor's visa? If yes, then (a) should they apply as if they are going for new visa or (b) apply as if going for re-stamping of current visa (which is clearly visible in their old passports)?
Don't know if they re-stamp visitor's visa if it's still valid.
Which is the best option in this case? Need help urgently!!