First the interlining was interlocked to the wool face. We used the seam in the face fabric and then interlocked in alignment with where the rings would eventually be sewn.
Ribs were sewn to the interlining to provide additional structure.
Because in both rooms the underside of the boards are not easily visible, we did not need to make returns, but we did use a bit of trim to cover the ends of the boards.
The time we spent on steps to support and stabilize the wool were well spent.