Leave this duplicate for now and go back to the original geometry. Select the edges shown in green and chamfer them by 0.8 or so. Make sure you do not deselect the currently selected edges because we will need them in a bit
and it will be a pain in the A** to have to go through and select them all again.
Go into polygon mode and select the thin line of polygons created by the chamfer (shown in red) and extrude them outwards by about 0.8. This will form a thin ridge of polys. Adjust if necessary to get the shape right.
Now go back into edge mode and those edges from before should still be selected. If not, reselect them. Chamfer those edges by 0.05 and when you smooth the geometry, there should be a nice ridge around the cushion as shown. So you basically do a double chamfer here.