Today we will have a look at re harmonising with extra dominant substitutions and a chord ii variant…..
The first bar employs a C6/9 in place of the basic tonic chord of C major.
Also, note that this has a 3/4 time signature and starts with an up beat.
The next two bars alter the Dominant chord of G7. This is achieved by thinking of G as a 1st inversion and changing the harmony on top.
The BbmMaj7/B has the flattened 3rd like a #9 a flattened 5th [altered] but has the 9th and the 7th of G7. The first 4 notes of the improvised line establishes the BbmMaj7/B harmony whilst the next eight notes employ the A whole tone scale.
The next substitution is a Db chord over the B bass establishing the flattened 5th and a flattened 9th. But, what is really happening is that we are taking a triad a tritone away form the dominant chord G7 and superimposing that on the B [as a 1st inversion] bass note.
Next, we use a chord ii substitution. Again, thinking of F as the bass [1st inversion] we play an E triad over the top. This has the raised 6th and the flattened 5th as a sort of m7b5/Dorian mix.
The final Dominant substitution employs another triad from G altered. This time we use the Eb triad over the B [as 1st inversion] bass. [This has an added 9th acting as the 7th note of G]