You might not be able to tell at first glance that the left and right sides are different widths. The swoop on the right is about 1" wider than the left swoop.
Custom Workroom Weekend last October, and again at the Custom Workroom Conference coming up in May. I made dozens of samples in order to compile data on the effect of swoop width on the droop length of relaxed roman shade.
To avoid pinholes of light coming through the blackout layer at the ring stitches, I overlapped the widths at the center. Underneath you can see the basting line at the face fabric seam, so I could tell where to put the rings.
I used my two-layer no-pinholes ring sewing technique.
The overlapping layer was then glued down. You might be able to see a row of fusible adhesive- which I tried first- but without blackout lining those tapes don't always adhere securely, so I switched to tried-and-true fringe adhesive.
We had a happy customer!