Originally Posted by
findark
You can certainly change to a different routing, but expect to pay the change fee unless the change is eligible for SDC.
And any difference in fare, which could be considerable, especially on the outbound, because it will reprice the ticket using a no-advance-purchase fare.
Flights operated by LH are not eligible for SDC, although some agents may do it anyway when moving to UA-operated flights.
If there is LH I space, I'd probably book the LH flight and then hold my breath. If not, I'd probably bite the bullet and transit the US if there are confirmable upgrades in advance.