I saw BBD just once, opening for BOC at the Boston Music Hall on March 31, '78. At the time I did not know Charlie's role on backing vocals, but I was very surprised to see the bassist looked nothing like him. It's hard to say what he looked like, the bassist had very long, very straight black hair which he wore in such a way that it obscured his face pretty much entirely, and I don't remember him taking part in any vocals. I have a memory of seeing the band on US TV once during that tour as well, and seeing this same bassist. While the veracity of the TV appearance memory is rather suspect at this point, the concert memory is very strong & clear. A search of the forums here netted me no insights, so I thought I'd ask. This player knew the whole set and the band sounded great, so I would guess he played for the entire tour.