The ITA flight was not on a separate fare. It was part of a single UA fare. UA has an interline agreement with ITA to include flights on it's metal (limited to flights within EU) on trips booked on UA fares and UA splits some of the revenue from the fare with ITA. LH also has an interline flight booking agreement with them. The ITA flights will be ITA coded with one of ITAs booking classes which don't really have much to do with with UA fare and class you booked other than sharing the same class of service as your UA booking.