Originally Posted by
Xyzzy
Did at least one of those LH flights have a UA flight number associated with it? I suspect s

...
.com will sell intra-Europe LH flights under the native flight number. Just go search MUC-FCO, to give but one example.
There are many instances in which UA will sell partner flights with no UA segment or codeshare on the itinerary. Though typically not if UA offers an alternative on its own metal.