Its unfortunate that they have gone thru this, but they themselves are responsible for this. No one in their proper mind would forget old passports and visas unless they were living in isolation with other desi community. No one should take it granted that you can bypass the rules if you are an NRI. Would these parents expect a different treatment incase they were in a different country?
And then if transit was granted to the frenchman mentioned by breaking the rules, certainly action should be taken against the officials.
