This change is a bit more destructive to the pattern, as it involves actually cutting, stretching and taping the original. I suppose I could have traced off another sleeve, and cut that, but I wanted to see if this was going to work, and didn’t feel like spending a lot of time on it.
In the photo above, you can see where I drew the vertical grain line, and a horizontal line where I needed the width. You leave little paper hinges at the edge of the pattern, then gently pull it apart at the armscye. That has the effect of both lowering the sleeve cap, adding bicep width, and not at all changing the length of the sleeve head. Pretty nifty!
I still have to true up the bottom of the sleeve, but that is easily done. The sleeves on the muslin fit just fine. I’m still debating about the back, if I need to add a bit more to the width adjustment or not. Better try that muslin on again!