No one sings unless we sit together (at the job) and get their key and the name of the song. Backing up a singer in any key was not a problem. Finding their key once they started to sing took a few measures but we got there. If they look like they do not have it together I put them off till later in the evening, which never happened � followed by an apology of course, it�s business.
If they sing well and the audience likes them we go for an encore. If they are bad I normally take the mic and ask for applause, then I do not return the mic.

I once played for a woman who sang terribly, she made an error and turned and looked at the band with an expression on her face like putting the blame on the band. In the middle of the next chorus I told the band to change key of the song, they booed her off. Aaaaaah.

With a live band I never worried about losing control, we had the instrument and we owned the mic --- and I controlled what happened on the bandstand.

As a OMB I would have doubts, to busy working the keyboard and trying to back up the singer to be in control. If I were using midi files, I would not touch it � very, very little control over what is happening.

John C.