There are people who cannot sing. A dear friend of mine liked singing very much but could not keep the tune. I tried to train him, but in vain. So I told him to sing with the crew, but only piano to pianissimo. It worked well.
The same happened to me. When I lost my singing capacities due to an accident (even the vocal chords know the parting trauma) I followed this advice, too. When we meet with other friends and sing jolly drinking songs we do it also in fear that we have to do it as duo, the others turned over by our voices and rolling around with lots of laughter. But we enjoy it.

Wilfried