Let's take Autumn Leaves. When we move to relative minor on the 5th bar, the progression is: F#ø7 - B7b9 - Emi7 - etc We pluck the dom7 chord here from harmonic minor. So because of this we have available as tensions (or extensions) a b9 and a b13. Correct so far? Now I've heard that a #9 is also available. Is this because it this tone is part of the original major (and also the relative minor) harmony (context) into which this dom7 chord has been placed? I know that it all depends on what you are hearing, what everybody else is playing at that moment, et cetera, but I would like understand the 'logic' behind this.