Principle 29.2.1. Voice Leading Borrowed Chords.
Resolve ♭\(\hat{6} \) down by step when it is a chord member of a borrowed chord.
Section 29.2 Voice Leading Borrowed Chords
Borrowed chords, or chords making use of mode mixture, are handled similarly to their diatonic versions in terms of voice leading, e.g., \(\left.\text{ii}^ø{}^{7}\right.\) is handled similarly to \(\left.\text{ii}^{7}\right.\). In any of the borrowed chords with ♭\(\hat{6} \), resolve this tendency tone down by step whenever possible.
Another situation where you may encounter a borrowed chord is the \(\left.\text{V}\right.\)–♭\(\left.\text{VI}\right.\) cadence, which should be handled the same as the deceptive cadence in minor (see Principle 26.7.4)—resolve the 3rd of the \(\left.\text{V}\right.\) chord up by step and move the other two voices in contrary motion to the bass.
There are no specific rules for other borrowed chords such as ♭\(\left.\text{III}\right.\), ♭\(\left.\text{VII}\right.\), \(\left.\text{i}\right.\), and \(\left.\text{v}\right.\); simply voice lead them as smoothly as possible while avoiding objectionable parallels.
