I just learned that Corey Christiansen will be teaching an 8-week course in chord substitution via an online learning platform called Jazz Anywhere. I have attended two week-long classes taught by Corey in a live setting. I found him to be a talented instructor and an all around nice guy. He created a great vibe in the classroom. I expect he'll do the same with a live, online course. I have been putting a lot of time into my chords so I'm looking forward to this. I'm not affiliated with the course in any way, but I thought folks here may be interested in learning more about it, too.

Here is a link to Jazz Anywhere. Look for the course called, It's About the Subs.