To convert my version of the ceremonial gown into the poster gown, I unpicked the side seams until about fingertip length (the point on my thigh where my middle finger touches when my arms are at my sides). The dress needed to be lined, so I cut out another back from Simplicity 8937 and lengthened it to match the dress. For the front, I just traced the front of my dress to get the right shape, since it had been altered a good bit from the original pattern piece. Lining it was then simply a matter of attaching the lining and the dress at the bottom right sides together so that the seam allowance would be on the inside when turned right side out, turning the lining to the inside, sewing up the side seams, and securing the top of the lining to the dress facing. This was a little bit tricky in front, because of the bust seam—I had to "stitch in the ditch" from the front so that there wasn't any extra stitching showing through in front. After everything was assembled I also adjusted the back darts to conform to my back more.

Altering and lining the darn thing was much easier than originally creating it. I almost wish I had done this years ago!