Many thanks to all of you who answered my call for feedback about adding the center medallion to Norma's Cake Doyley. With a fair amount of trepidation, I decided to add the center medallion. It's done and delivered, and Mom was thrilled with it.
Norma suggested using the buttonhole stitch to sew around the motif, catching the outer picots as you sew. The first thing I had to do was an internet search for instructions on the buttonhole stitch. For a first effort, it came out pretty well. I was really nervous about cutting the fabric away behind the lace, but so glad I did once I saw the difference it makes. Laying the lace atop the fabric circle really didn't give me a clear idea of what it would look like once the fabric behind it was removed.