As a matter of fact . . . Boo sat in with me on a couple of gigs, and we had a great time. By the end of the weekend he was saying "Ya'll Come Back Now, Ya Here?"
I later took him to another club where he sat in with some friends of mine and was a big hit there also.
I'm sure we had a couple of guest singers while he was playing. It all depends on the circumstances.
DonM