you could mark circles around the inserted "diamond" with a marker or use a plastic Hera marker and follow the indentations it makes. then use the width of your presser foot to do another circle outside that one till you fill the blocks.
I did each square on mine with some FMQ sort of flower design. just something to fill them enough. I didn't stitch my diamonds down at all because some were only folded over to make 3D flying geese and some blks had none.
think on it and something will come to you. good luck.