Thanks Tom, not our best advert. As a musician you'll appreciate how tough it is to keep them all in sync'.
Some folks can't even remember to bring the correct music, and I have to bring extra copies to concerts and "switch them out" at the last minute. One or two folks don't remember which instrument to play and when (ukulele vs banjo ukulele); A banjouke doesn't sound good on a Hawaiian number

So I plant folks at strategic locations in the seating chart at concerts to keep an eye on the folks who need help, and I mark the music in large, bold, red letters to identify which instrument to play and when.
The seating charts also get modified to help the folks who are hard of hearing, especially the folks who play/sing off the beat and, in some cases, might be several lines out of sync'. In these cases, I plant "loud" singers either side of them.
As I tell my other half, I just hope folks will look out for me when I get to that point.