My recollection is any inter-zone UA flight; it need not be the first. I had no issue with HKG>FRA>TLV(LH) / TLV>MUC>STR(LH) / TLV>FRA>JFK(LH) / LGA>ORD(UA) / ORD>HKG(UA) in A/C classes on 016 stock back when all those routes had LH F and UA F. (In that case, UA was the last segment). UA issued the ticket-- and by UA, I mean a UA phone agent calculated the fare and it was issued at the UA ticket counter at the HKG airport and then I walked over to LH to check in. I had other similar ones; I tried to originate them overseas because the fares were lower than ex-US. There was no one else in the in the LH F cabin between TLV and MUC-- that might help explain why they no longer offer F (or real C) in that market.