Interesting challenge. No answers I'm afraid, just wanted to check in, tell ya we're giving a listen.

Your number 4 singer is a good ballad singer who reminds me of Jim McCann, but from the simple guitar only arrangement one has to suspect a good demo from a performer who is only known locally. Our best bet is if someone who digs through demo tapes to book for Celtic festivals recognizes somebody.

Sorry I can't help, but we're tryin'!