Sorry, can't help with that, but hopefully someone will.

Going back to what Joe was saying, I play piano/keyboard in a couple of ceilidh bands, and our music is as he says, a line of melody plus chords, no left hand written out. Yes, I could work out what chords to play on the hoof, but then the accordionist might go for something different. It helps that we are playing "from the same hymn sheet "!