There are very brief glimpses of the Bramletts (Delaney and Bonnie, separately) on the train in the opening few minutes of the film, but never on stage and never with their band (whoever might have been in the band at the time). I think we might hear one or the other them sing a line or two in that informal on-the-train "jam" context.

I don't know what became of them, either. Leon Russel and Eric Clapton both played with their group at some point(s) in time, and Clapton stole the core group of players in their "and Friends" band to become "the Dominoes" of "Derek and..." After the loss of those three guys, I'm not sure that D&B continued their performing careers at all...

Yeah, wasn't Rick Danko just great? I have to believe that his tragic early demise was more "accidental" than those of so many of his drugged-out contemporaries. I mean, I know for a fact that never hesitated to get high at the slightest provocation, but he never projected the persona of a self-obssessed junky superstar; he always seemed like a very affable and "regular" guy, albeit an abnormally talented one...