I have an Elise Hayden duet. I play from music that is not made for concertina (namely flute, piano, and sax) This music is not made for concertina, and thus has sharps and flats that don't exist on my concertina. I was wondering if there is a substitute for those notes. Should I shift down or up a few notes so the sharps and flats I do have can line up with the notes that need them or what? I am playing a lamentation so the small difference between sharp, flat and natural is pretty audible. Any suggestions help please.