Now that we have a fitted bodice we should make sure that the sleeves are good. I decided to lengthen my sleeve and here are the instructions for how I did it. You only need to make one of the sleeves for the muslin.
Since I took the sideseam in by 1/4 " then I needed to do that same to my sleeve so that the armhole matched up to the bodice. I started with 1/4" at the armpit and then gradually adjusted it to 0" about halfway down the arm.
Then, with right sides together, I basted the sleeve together at 5/8" under the armhole.
Next, I pinned the sleeve to the bodice with right sides together at the armhole.
Then I stitched them together with a basting stitch at 5/8". There will be a bit of extra fabric at the top of the armhole on the sleeve. You will need to gently slip the excess in the seam so that there is a small bit more fabric on the sleeve but the fabric is more taute on the bodice. This is called easing. This allows for your sleeve to move more freely. (remember this is the muslin so don't worry if it isn't perfect)
Now try it on and see if there are any changes. Mark where you want the sleeve to end and then add on another 1 1/2" for hemming.
Now to transfer any changes to my pattern piece. First I added a piece of tissue paper and marked where I wanted my sleeve to end (adding in 1 1/2" for hemming).
Then I added my adjustments for the sleeve with and cut the remaining tissue paper off.