Hello Hans & all   You might be interested to have a look at the layout of my Levitina. It's a very special instrument, built by Emanuel Pariselle in 2013, a hybrid anglo/bandoneon/accordion, with two sets of reeds tuned one octave apart. It can be switched to baritone, treble of both ! This one is C/G and my numbering of octave is different fro yours, but I thing you can easily figure out what it would be in G/D. Emannuel managed to fit 37 buttons (with one lit