I second Richard Bridge on this one. You should not be memorizing a chart, you should be learning to rely on counting. Now that you have majors and minors, do you want another chart for sixths, another for sevenths, another for minor sevenths, another for ninths, another for ....? They all work the same way. My advice is to make friends with a piano and pick out a C-major scale on it--just that. Period. Notice where the black keys are and are not, and by next week you will be legendary. (Unless you are already, in which case you'll be super-legendary.)

But you are on to a good thing with Nick, about two people not playing in the same position. My very first musical experience was jamming regularly with two other guys. I was the newbie, so I got to play first position rhythm. (This was all on four-string banjos, by the way, but it matters not.) The second guy played the melody, usually somewhere around the fifth fret. The third played high harmonies, way up the neck. In our better moments, we were almost .... orchestral. Well, almost.

Chicken Charlie