How about giving them an instrumental break and singing over it? Nah, they wouldn't get it. Sometimes it works to just say something. You can say almost anything and get away with it if: You are big and mean looking, if you a small and sweet, or if you are respected. When I made my most recent tape/cd the fiddler played his fiddle well enough, but, it wasn't the sound I wanted, so, I asked him to do it over on the viola. He was glad to, and, I'm glad I asked him. The harmonica player tended to slip into "Goodnight Ladies" behind Phoebe Snow, and, when I mentioned it, he tried to change what he was doing with no hissy fit crap. The secret? Use "I" messages, not "you" messages.