Thanks for the info.

Incidentally, my parents could not get the UA MP number onto the flight. The Air India agents who handle the ground service for AuA had no clue how to deal with it.

Since all is well that ends well (and there is no way of figuring out who was to blame for this) I have decided not even to write a "polite letter".

I am still interested in knowing if there is any way of pursuing legal action in the United States when a carrier flying into the US screws up outside the US. Does the ticket have to be purchased in the US for the US laws to be valid? Does the flight have to start in the US (regardless of where the ticket is being purchased from)?

I hope I do not get into a situation like this again, but it is always good to know .