Rules narrowed down: chord substitution

Below are a group of the near-finalised versions of the chord substitution based rules.  These may change before the final ruleset is released.

1) Dominant 7th chords may be replaced by minor seventh chords (eg. B7 can become Bm7) ONLY if the melody note does not fall upon the major third.  (This minor seven chord can then become the introduction to an imposed ii-V sequence).

2) Similarly, minor chords can be replaced with dominant seventh chords.  Same rules as above apply.

3) Any major triad can be made into a major 7 - those major 7 chords can then be replaced by the related mIII or mVI (eg. Cmaj 7 may be substituted for Em7 or Am7).

4) Those substituted chords may then be replaced by their major counterpart - e.g., Em7 may then become Gmaj 7.  Rule 3 can then apply to the same Gmaj7.  By doing this you can get a Bm7 chord from a Cmaj7 chord - MELODY DEPENDENT. 

5) If going into a ii-V especially, the ii chord can be substituted for a ii#9 b 5 chord.

Tritone Substitution

1) Any dominant seventh chord can be replaced by it's tritone substitute if THE MELODY DOES NOT FALL WITHIN A SEMI-TONE OF THE CHORD'S GUIDE TONES.  Eg. G7 can become Db7/G, or G7/Db, etc...

2) Tritone substitution should be used sparingly.  Do not alter every dominant chord into it's tritone substitute.  Tritone substitute should be used for colour, especially near the end of lines where a resolution is likely.

3) ONLY WHEN IT DOES NOT CONFLICT WITH THE MELODY you may alter the tritone chord even more - instead of flattening the fifth and 9th, sharpen them and play them on top of the tritone.  Eg. F7-Bbmaj7 - B7/Db7 - Bb (tritone/altered chord - Bb).  Again, this should only be used sparingly, preferably at the end of lines to build tension.