Sometimes when you want to "decorate" a chord (this is my term, and I merely mean adding a 6th, aug., 9th or 7th etc.) you have to change the initial fingering to accomodate the new chord. This isn't easy (that's why most folks don't do it) and involves VERY quick finger movement. I try to stress the "gliding" of fingers rather than lifting them up and down. Yah it's a bitch...but oh, the rewards.

Rick