The choice of the 4 most pertinent and logical minor Keys seemed evident -
         first the 3 minor chords of the Diatonic Window, the ANTEs,
                   D Minor, A Minor, and E Minor, with preference to the relative minor,
         and then the Dominantized COUNTER-DOMINANT [IVm] F Minor.

C Major To A Minor

The Key of A minor, as relative minor of the Key of C major,
         certainly deserves to be seen first.

The A minor Circle, despite its melodic ternary appearance,
         has evidently maintained its original harmonic binary form,
                   but the major cadence (G⁷ - C⁺⁷, chords 3 and 4) has been even further attenuated.
One could not ask for a better melodic fit between the two circles,
         the A minor circle starting on the last note of the C major circle.

C Major To D Minor

The D minor Circle has also maintained its original harmonic binary form,
                   with the major cadence (C⁷ - F⁺⁷, chords 3 and 4) also attenuated.
         In order to reach the Key signature of 1 flat, chords 1 and 2 are Dominantized.

C Major To E Minor

The E minor Circle has also maintained its original harmonic binary form,
                   with the major cadence (D⁷ - G⁺⁷, chords 3 and 4) also attenuated.
         In order to reach the Key signature of 1 sharp, chords 1 and 2 may be left diatonic,
                   since they are common to the 2 Key signatures.

C Major To F Minor

The F minor Circle has also maintained its original harmonic binary form,
                   with the major cadence (Eb⁷ - Ab⁺⁷, chords 3 and 4) also attenuated.
         In order to reach the Key signature of 4 flats, chords 1 and 2 are Dominantized.

Minor To Major