Part Writing Secondary Dominant Chords
The voice leading of secondary dominant chords is the same as for primary dominant chords. Secondary dominant triads require that you carefully maintain recommended doublings because the third of the chord has the function of a leading tone and should not be doubled. All other conventional part-writing practices apply. Resolve the seventh of the V7/ chord down one scale degree in the same voice. It is important to remember that all four factors of the V7/ are usually present, but for smoothness of voice leading, the fifth may be omitted and the root doubled.
Part Writing Secondary Leading-Tone Chords
The voice leading of secondary leading-tone chords is the same as for primary leading tone chords. For viio6/ there is no established voice-leading pattern, but the bass note should be doubled, avoiding skips of a tritone, and all voices should move with as much stepwise movement as possible. Avoid doubling the root of a secondary leading-tone triad because the root functions as a leading tone and should never be doubled.
For the secondary leading-tone seventh chords, resolve the seventh of the viiØ7/ or viiø7/ (and inversions) down one diatonic scale degree. Resolve the tritone (root to fifth) inward if a d5th and outward if an A4th. However, it is not possible to do so in all situations.