Mrs. Bloxomo and I (both silver) recently flew HEL-FRA-IAD with HEL-FRA on LH and FRA-IAD operated by UA (ticked as an LH codeshare) and found it difficult to change to E+.

At T-24 I checked in online with LH, but of course one can't change UA seat assignments through the LH site. Since my 1st flight was on LH I could not use the UA site to change seats and reprint boarding passes. So I called UA to get seats assigned in E+ but was told I'd have to pay since it was T-30 to the UA FRA-IAD flight -- I did point out to no avail that the online elite benefits table says silvers get E+ "at check-in", not at T-24.

I called back at T-30 but at that point the seat map was under airport control so the phone agents and one supervisor couldn't do anything (or couldn't figure out how to do what they needed to do). They said I'd have to wait to change at the gate.

Of course, E+ supply was rapidly dwindling and by the time we got to FRA and waited for the gate to open there was no E+ left. We had to pester the gate agents one last time just after they closed check-in to snag two seats in adjacent rows vacated by people who had missed the flight. (But it turns out one seat was then double-booked and it took a couple calls back to the gate and a swap with another pax to get us next to each other somewhere else.)

Fortunately I'll make Gold this year so I won't have to deal with it for a while, but is there an easier way to do this? I think this is a fairly common situation, so it seems like there has to be a better way.

I haven't had an experience with this myself, but were you able to obtain the UA confirmation code from LH?... then maybe you could access the seat map online on the UA website. I'm assuming you were crediting the miles to UA and not LH?

Yes, I had the UA confirmation number and the flight was showing up in my united.com account.

The problem is that once you've checked in (and any time after T-24, I think?) the only way to change seat assignments is through the UA check-in process -- there was a link to that on the "view/change seats" page for the FRA-IAD flight, but in this case following the link resulted in an error message directing me to use the LH site -- I suspect that was because the first flight (and hence the one I would check in for) was on LH.

I was wondering about this too recently as I had a KOJ-HND-LAX-PDX itinerary on NH with the LAX-PDX segment on UA. However, I was lucky enough to be given a F upgrade T-24 or 48 on a holiday weekend, so never directly dealt with the situation. I would love to know the answer, though.

So far the only thing I can think of is to call at T-24.5 right before the seat map goes over to airport control. Then maybe the phone reps would be more likely to waive the E+ fee when given an explanation that it will be difficult to change the seats later.

This is possible, although I would imagine unlikely. However, it's not much help if it's the middle of the night or one is already in the air. Logic would say that there has to be a way, but UA's implementation of changes to their systems seems so poor currently that I fear that this scenario may never have been contemplated by those managing the change.

Does it help if you wait until 24 hours before the UA segment and check in for the UA segment first before checking in with LH? Of course you might be at a disadvantage for LH seat selection that way.

I don't think you can check in for just the second segment like that.