Hi this might sound stupid but when we travel to Las Vegas in two weeks time we will be making 3 flights in total with 2 connecting flights, one at London Heathrow and another at Chicago. When we book our luggage in to fly to Heathrow will it be forwarded onto our United flight to Chicago or will we have to collect it and book it onto the Chicago flight. Also, as Chicago will be our entry point into the USA, will we have to collect it there to pass through customs or will it again be forwarded onto our United flight to LV. Or alternatively, will we arrive at Vegas just as our luggage is arriving in Karachi. Always took direct flights in the past so this is an adventure in itself