1. Add length to the upper part of the pattern, making a 90 degree line to the straight of grain line, cut the pattern and add the extra length (I used 4cm).
The amount needed I measured by comparing the pattern piece to my actual length from shoulder to under my breast.
Don't forget to make this change to the back pattern part and the front band.
This lengthening of the pattern is needed to make sure that the band goes below the breast, and not ends up on your breast.

2. Mark the amount to widen the top in the front, in my case I thought 2 cm would be enough (which of course makes a total of 4 cm extra width in the end).
3. Pivot from top to the marked point. Draw a new line from pivot point to marked point.

4. The marked point to widen the top is used as second pivot point. Pivot the pattern to the seam line. Mark the line.
The pattern is now changed, armhole and sideseam have not changed, but extra width is added.
