Part 1 Bib construction
Sew the lace down both sides. Then sew around the bib portion using a straight stitch.
Next, prepare the ruffle. Cut a strip of fabric 1 3/4" x 23".
I don't have a serger so I did a rolled hem on the strip of fabric - which is just turning it twice as narrow as you can and sew along the fold.
Get out your pins and start fussing with the ruffle to get it to fit. I use a lot of pins in this process so it fits perfectly. Make adjustments in the ruffle as necessary.
Part 2 - Skirt Construction
You can tell from the photos it is getting later and later and I am getting tired-er. My photos aren't the best. Essentially you are making a little gathered skirt and sewing it to the onsie.
Cut your skirt fabric 11 1/2"x 34".
My onsie is size 3 to 9 months. (That's a new size to me. My youngest is 5 and I never had onsies made that size!) If your onsie is larger I would add a little to both measurements.
With right sides together, sew the two edges together to form the back seam. You will have a continuous piece. Press the seams open or zigzag the edges. My seam allowance was a generous quarter inch. It doesn't really matter on this project.
Now we are ready to gather. Sew a gathering stitch around your skirt waist about 1/4 inches below your top hem. Pictured below:
Dress Hem: You can hem the dress how ever you like. I was going to sew a small ruffle along the hem in coordinating fabric but I ran out of time. So I did a lace hem. I sewed the lace and pressed it out and top stitched it down. You could use ric rac, or other decorative trim, or you can sew a regular hem.
Here it is!! I also sewed a matching flower for the baby's head - but I finished it on my way out the door to mail it - so no photo :(