The final pattern. Really easy. I know I always say that, but I guess that once you know how to do something it usually is easy. The pattern looks a little like a pair of overalls!!
To sew the top portion of the sleeve, bring the two extensions together and sew the 1/4" seam allowance. Then bring that seam line down to the sleeve and match that seam line to the center of the sleeve. Sew the joined extensions to the top of the sleeve with a 1/4" seam. Once this is done, sew the sleeve to the garment as you usually would.