Let's bring back the Keyboard Chord Decoder and figure out just how much we can get out of this one handy little Ddim7. In 4(a), you can see how to create each of the four related dominant seventh chords by lowering each of the notes of the Ddim7 by a half-step; the lowered note is the root of the new dominant seventh chord. In the music for 4(a), our borrowing gives us a Db7 on beat 1 of bar 1, an E7 on beat 2 (both over a Bb root), and an Abmin7b5 over an E on beat 3—the latter can be looked at as an E9, which is one of the related dominants from the family of the "chord below."

Keyboard Chord Decoder 2 The family of related dominants in the "chord below"