(Started a new topic, since the "Shand Morino" thread has wandered a bit).
The solution to the missing Bminor, F#minor etc chords on the stradella 48-bass with 8x6 layout is to use minor 7th chords. These are used by Scottish PA accordionist Sandy Brechin on his tuition video "Play Scottish Accordion". Sandy is a wizard on a 48-bass Hohner PA (although the video features a larger Guerrini).
The minor 7th chords are formed thus:
B (counterbass in G row) + Dmajor (row above) = Bm7
F# (counterbass of D) + Amajor = F#m7
C# (counterbass of A) + Emajor = C#m7
Suggested fingering is ring (4th) finger on counterbass, index (2nd) finger on major chord.
Usually these sound OK in place of the "missing" Bminor etc chords. Sometimes the B, F#, C# bass notes from the counterbass row (column?) are suitable substitutes for Bm, B7, etc.