I sewed each plate together then centered them in the block and satin stich all the way around I used a glass to make the center circle.
to hold in place to satin stitch I use a washable kids glue stick on the center and every few petals
If you go to the address you can see the one I did and how I did it hope it helps you
http://www.quiltingboard.com/posts/list/491.page