Ok, I know you can use a SWU to upgrade a UA flight. And I know you can use a SWU to upgrade a LH flight, provided you plan ahead for a paper cert or are willing to waitlist on the day of departure.

But say you have an itinery like IAD-FRA(UA), FRA-CDG(LH). You submit your e-SWU, the upgrade clears (Y to C) for the UA leg, and your seats are assigned (upper deck, yay!).

The UA agent tells me that's it, you're done, the SWU doesn't cover any LH legs. But I've heard hints and innuendo here on FT that the person checking me in on the day of departure can waitlist me for an upgrade on the LH leg - as an extension of the original (single) SWU.

Anyone have any experience with this?

Now, I know intra-Europe on LH it's the same ole' seat, etc, just hoping for a better snack box...