Steve

My grasp of modes (of the major scale at least) is excellent, Steve.

If you have the notes for G major you have by definition all the notes for all the modes of that scale: ionian, dorian, phrygian, lydian, mixolydian, aeolian, lochrian.

It isn't a question of what is doable on diatonic instruments: it's a question of 1) what is doable on a two row melodeon which has basically one octave of the ionian with a few other notes thrown in at each end of the octave 2) which of those modes end with a pull and which with a push - this linking to WP's belief that older songs ended with a pull, and 3) how these might or might not relate to the tunes Pardon played on a melodeon and the differences between the melodies Pardon had and the melodies people were used to hearing.