Joerg, I guess I am talking about 'decorating' some of the chords with additional notes. Sometimes I want to place my available finger near the next fret, but I may not have gotten that particular finger to stretch that far as of yet with the particular chord-hand positioning I am working with.
Does that make more sense?

I can get some sustain out of the notes I play on the banjo but this is usually when I am playing a melodic tune. With bluegrass and oldtime music, the focus as I understand it, is not to achieve sustain but rather the notes are purposely deaden by the speed and other things are more important like intonation.
But sometimes I like to play the banjo in an 'uncharacteristical' way too. I try to bring out as much sustain a possible.

BB