Allman Brothers Band. On more than one occasion played an entire 3 hr show without Gregg Allman (due to effects of his therapy for Hep-C, prior to his liver transplant)

Little Feat. Drummer Richie Hayward couldn't make it through a show due to after effects of chemotherapy treatment; his roadie Gabe Ford filled in. After Richie died, Gabe Ford became Little Feat's full-time drummer.

I've played gigs where a key member of the band has been ill & gotten through the night. At a gig a few years ago, our bass player passed out on stage from effects of shortness of breath at the start of our 2nd set (we played 5 sets) We called 911...they wheeled him out on a gurney with an oxygen mask, and as they did he told me "Use my bass, finish the gig". So, I did, I switched to playing bass, we played the remaining sets. 3 hours after the gig ended, I got a phone call...our bass player had died.

It can be done, just whether the band can be flexible & spontaneous enough to get through it. (and we know how UNspontaneous Fleetwood Mac is)

Metallica did it in 2004...
 

Sorry to hear about your bass player chiliD.It must have been a shock to you all and I'm glad you finished out the gig.:angel:

You said a mouthful brother.

Three singer songwriters that have been touring
for over forty years can't contribute 3 songs off
the cuff. Something's wrong there.