Hi freefall565,

Let's try this first,  take your clothing item and check your end points for the shoulders and abdomen in the joint editor.  (They will be red cross hairs)  Make sure your shoulder end points match Koshini 2's forearm start points ( Start points are green cross hairs)  Likewise,  make sure your abdomen end point matches Koshini 2's hip start point.  Also,  make sure Inverse Kinetics is turned off for your clothing item.

Cheers,
Patorak