Step 1

Lay dress shirt out nice and flat. Find a romper that fits your child and lay it on top of the dress shirt lining up the collars and upper arm/shoulder seams

Step 2

Cut the dress shirt around the existing romper (being careful not to accidentally cut the romper one though). One mistake that I am still trying to remedy is that I keep cutting the lower leg/ankle area too narrow ... just an FYI to be generous there.

Step 3

Looking at the size of the ribbing on the existing romper, cut cuffs for the wrists and ankles (you can also find an appropriate pattern piece for this in your KS book or something). Next serge the wrist ribbing to the sleeve.

Step 4

Sew the under arm seam all the way down to the ankle.

Step 5

Add ribbing to ankles. sew a strip of bias tape, right sides together, to each of the inside leg seams (I turned the bias tape up to finish edge before I started serging). Turn bias tape to inside and topstitch, hiding folded up end of bias tape and any serging tails. Add snaps.