I also had travelled recently(Dec-Jan) to KTM via Delhi. It was by JET AIRWAYS. The flight was from JFK to Brussels-Delhi-KTM. I checked in luggage at JFK and picked KTM airport. At Delhi, DO NOT GO TO EXIT or IMMIGRATION CHECK LINE. LOOK FOR AIRLINES AGENT. They will record your names and check the ticket and baggage claim ticket. FOLLOW THE AGENT. Then they take you to the transit lounge. All passengers travelling to Nepal should stay whole night in the transit because the flight to Nepal is in the morning. But there are some chairs suitable to sleep and strech your legs (though you can not sleep as they make announcement every minute). So going to Nepal is usual. But there is something different while returing as most of friends mentioned.

Return flight:

I checked in the luggage at KTM airport. They also gave the boarding passes all the way to JFK (it was in Royal Nepal Airlines pad, (must be old left)) without barcode. Boarding pass works only upto Delhi and should have barcode onward. AGAIN at Delhi airport, the airlines agent record your passport #, baggage ticket and takes you to the same transit lounge. I did not need to worry about baggage. There was almost like 8 hour transit at night.

Yes, agent comes and takes your passport. I knew that from other friends, so it was not a horror story for me. There were 6 nepalese travelling. We asked the name of the agent before giving the passport. In an hour, he brought back the passport and new boarding pass with barcode and some baggage tag (you need to put the babbage tag in each handbags with your name and get stamped in the security check). In the meantime they also gave dinner box. The food was very hot (marich ko piro), I ate all though. CHECK YOUE BOARDING TIME and GATE. After security check i boarded in time and landed at JFK.

The ticket price was cheaper via Delhi, transit was longer.