Originally Posted by
Shanghighx
The flight in question AA154 NRT-ORD shows in EF as C2 AA154 NRT-BOS shows as C0. It somehow makes sense, as ORD-BOS doesn't have a business class, so it can't have C inventory.
No, it doesn't: it has all business class inventories and they simply map to different cabins. There's something screwy on the through (NRTBOS) inventory: it never shows more than 2. Since you want to upgrade all 3 segments I'd personally go without splitting it and ask the EXP desk to queue the upgrade request to RM with a note explaining that there's availability on the underlying 2 segments that make the flight and if they could clear the through flight please. If that doesn't work (is denied for whatever reason), AFIK the EXP desk can then split the segments for you.