If you're on a *A award (a) where you connect from a flight on carrier A to a flight on carrier B; (b) purchased with the FF miles of carrier C; and (c) a downguage or route cancellation by carrier A forces you out of your ticketed class of service, I believe the strict letter of the law is that carrier C is responsible for "fixing" things even if in practice A and/or B will do what they can. The "fix," however, could involve keeping you in your ticketed class but may entail being downgraded and/or significantly delayed.

Several years ago I researched related issues regarding a *A ticket to Thailand. In the first place, I had a *A award purchased with UA miles involving the JFK-BKK nonstop on TG. At the time, there was talk that this route might be discontinued. My question was if TG cancelled the route, who, if anyone, was responsible for getting me to BKK in C. The answer was UA was responsible, but there was no absolute guarantee they could get me there in C. Whether or not they would have forced TG to fly me ex-LAX in C or opened up UA seats in C was something I could not ascertain. Bottom line was maybe, maybe not. I surmised in the end that UA would get me there but that if the TG flight was cancelled, but I could very well have faced a big fight to get C seats. (I ended up switching to SQ via FRA.)

The other issue was on the return. I had HKT-BKK on TG, connecting to SQ back to the U.S. The question was if TG had serious delays and made me miss the SQ flight out of BKK, what would happen? Who would fix it? The answer was the same as above: The award ticket was on UA stock, so UA would have to solve it. I would therefore be in a position of asking UA to fix a problem caused by TG -- not a pretty picture. Again, UA would have gotten me back to the US (somehow), but I don't know that I could have easily forced them to forgo a revenue seat to get me into C. (My hand would obviously be stronger if I was flying UA using UA miles.) In the end, I made sure I had a 5 hour connection in BKK.

So...to make a complicated story short, if the case you describe in Q3 came to pass in advance of the flights, UA would have to fix things, and given that the "problem" would be UA's "fault," you'd probably be taken care of. The cases you describe in Q4, though, os different because it would obviously occur after travel has commenced. Again, UA would be responsbile for fixing things with LH. In the case of Q5, I think you'd be okay because up to that point you're dealing only with UA, but I would be on the horn with the 1K desk immediately to tell them what's going on.

Is your flight to ORD on UA? Are you indeed using UA miles for this?