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@Anonymous
Check the smoothing groups of of the new polygons you created via shift drag of the edges. It looks like they may be different than the adjoining polygons, hence the hard edge. If they are different smoothing groups, select all of the polygons on either side of the edge you don't like and click on "Clear All" in the smoothing groups section of the Editable Poly Rollout. You can also assign a new smoothing group to the selected polys to have Max smooth over the selected area depending on the look you want.
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