Before you sew the bodice, you need to bind the neck and armhole edges.
You will make some double-fold bias binding from the sleeves of the shirts.
1. Cut off 2 sleeves from one of the shirts.
2. Cut off the sleeve cuffs.
3. Cut the sleeve seam open, and open out the sleeve fabric flat.
4. Cut the sleeves on a 45 degree angle to create bias strips. The strips should be 1 1/2 inches wide. (about 4 cm)