So you are suggesting that in an Aria track:
1. Assume keysig has been set to C
2. Aria ScaleType Key
3. Now all the notes generated in an aria are base on a C Maj. scale, regardless of the chord setting.
Should be do-able.
But, will this not sound odd if in the piece we have, for example, a C7th chord (with a Bb) ... in this case the scale would be with a B and the chord with a Bb would be dissonant. Guess that'd be the users problem
Another idea might be to add a list of notes to aria and limit the picking from the list. So, in this case we'd ignore the scaletype completely. Don't know about the syntax off the top of my head, but something like:
aria Notelist c d e f g b
would limit to those notes.
This might be more useful. You could then have an aria based on only "C E B" or whatever.
Comments welcome.