I do have melody lines on the wish list, and will take a look at how we can support dyads/triads. If you've got a chart dyad/triad examples in a chart you wouldn't mind sharing, could you post it here (or you can send it to me directly via a forum "conversation")? I'm always on the lookout for how these types of things are being written.
About a shareable database for charts... could do that here, as long as the music isn't protected by copyright.
EDIT to add: If the "no copyright" restriction doesn't kill all interest in a sharable database, I can set up the database pretty quickly.
