Wish I was aware of that at the time. They said that I had to go to a transit counter for my LH b.p. because they weren't able to issue b.p. for the connection. Since I was in C, they should have told me I could get the b.p. at the Senator lounge. (and a RCC member, but they wouldn't assume that, I guess). AFTER getting my b.p. at the transit counter, I did go to the Senator lounge, which was a really nice place to wait for my connection.
On the return trip, LH gave me boarding passes even for the UA segments from FRA-SAN. Go figure. It's a good thing they did because even though I had 90 minutes to connect, I had to hike all over the airport taking elevators, a train, and go through security. Arrived at the gate after general boarding had started.