Add the ♭9 to the relative minor's dominant and the chord carries the exact half-step sting flamenco cadences are famous for — that ♭9 is the home key's 4 grinding against the borrowed3rd. Inside it hides a full dim7, which is why it resolves like one.
hear it in flamenco cadences · Gipsy Kings turnarounds
Lead-in — how players set it upFrom 6- itself — sting hardest returning to a place just left.Or from 4-, mist before the knife.Or bare: 1 straight to the sting, maximal contrast.Follow — where it usually goes6- walks the lane: 2-, 5⁷, and the major key resumes.Let 6- fall down the Andalusian stairs afterward.Or respell the hidden dim7 and exit somewhere new.
The ♭9 is the sting — the key's 4 grinding over the 3⁷. Hit it ON the beat, then drop it a half step onto the 6- chord's 3rd.Target tones (in C)E7♭9 — lean on G# (3) · D (b7)Am — lean on C (b3)Half-step wiresG# → A · B → C