In two recent issues of Down Beat (December 2011 & June 2013) and some recent issues of Just Jazz Guitar, there are articles on “poly chords”. Two chords stacked one upon the other, e.g. Cmaj7 plus Dmaj7.

This can be written as Cmaj7|Dmaj7 (Cmaj7 "pipe" Dmaj7), to distinguish between the "pipe" and the slash, as the slash is used to indicate a desired bass note (e.g. Am7/G).

Of course if one spells out the notes of Cmaj7/ Dmaj7: C, E, G, B, D, F#, A and C# one could use the tertian terms (for the Dmaj7 chord tones): 9, #11, 13, #15. This has however some unlucky consequences in BB, as #11 will alter the G in the C-chord and #15 is not recognized.

Hope you will find it worthwhile de develop a system for using poly chords and perhaps to create some Real (jazz) Styles.