old passports lost

[microdev1]

My parents got their passports renewed two years back.
But unfortunately, old passports are lost.
They actually visited US 15 years back and their visas were stamped in the old passports.
Is it important to carry both old and new passports for the interview?

[manishc]

I don't think that should be a problem. They can mention about prev visit in their DS-156. From there they can verify that claim.