|This sleeve alteration is from the Singer book "The Perfect Fit".
Even when I wasn't overweight, my beefy biceps meant that sleeves were always too tight. I find for my beefy arms that this is the best method of altering the pattern.
Draw a line across the sleeve, around 1" below the sleeve cap. Draw another line parallel to it around 4" higher. Divide the sleeve cap evenly into 3 and spread the outside segments by the amount needed. True the lines, smoothly.
This can be personalised, for example I add more to the sleeve back than the sleeve front.
If there is too much ease in the sleeve cap, you can add a small amount to the bodice side seams, tapering to nothing a couple of inches below the armscye.