When the upper bodice, in the shoulder area, is made smaller, the corresponding sleeve won't fit - because the bodice at the bottom of the armscye is now larger. In this case, the bodice is 1.5 inches larger at that point.
and the related sleeve adjustment:
This is a test sleeve to be sewn with the adjusted bodice pattern. It will need to be fitted from there. If the shoulder alterations are more complicated, the impact on the sleeve must be considered. For example, if the shoulder seam is moved forward, so is the sleeve cap.
more to come...