Thank you for help. I am transiting SJU, MIA, and LAX (arriving 5 minutes after midnight and departing 11:45 pm almost 24 hours later, so an overnight but not a stopover). I did find out that Malev flight Budapest to St. Petersburg is a code share on a non-permitted airline, so I am changing itinerary: FCO-HEL-LED. Unfortunately FCO-HEL on Finnair is economy only.