I know that pictures are often a huge help with instructions. The Jon-Jon pattern is very simple, but turning the leg openings can be a little confusing.
Here I have stitched together a Jon-Jon out of pale blue pique’ and lined it with white Imperial Broadcloth. I am now to Fig.18 in the pattern instructions. You may start with either leg opening. Hold the side seam of the outfit in one hand and the side seam of the lining in the other.
Still holding the side seams, pull them out away from each other and up and over the outfit. You will continue until they are pulled over the top of the outfit and the right sides of the outfit side seam and the lining side seam meet.
Pin the two side seams together. My right hand is holding the pinned seams and my left hand is holding one of the crotch openings. Fig.19 shows lining these up together, and preparing to pin.
I have now pinned across the entire length of the leg opening. Fig.20.
Stitch the entire length of the leg opening and trim the seam to about 1/4″. Fig.20
Fig.21 and 22, shows reaching into one of the crotch openings and pulling the outfit right side out. This picture shows me reaching in and by holding onto one of the shoulder piece, gently working the outfit right side out.
After turning the outfit right side out, you now have one leg opening completed. Follow the same instructions to complete the second leg opening. I am now ready to complete the crotch openings with snaps or buttons.