Scenario as follows:-
Shooting subject close to wall. With built in flash on D200 getting too much shadow behind subject. Reduce flash output by 2 stops & perfect exposure with minimal shadows.
Now move to SB800
Set to TTL - BL, shoot & get perfect exposure but too much shadow again. So on SB800 drop flash output by 2 stops via "select" button & shoot again. Now whole shot is 2 stops under exposed, plus still shadows.

D200 is in Aperture Priority mode, flash to front curtain.
So how do I drop the amount of "fill in" from SB800 without it causing the shot to beunder exposed ?