
Step 1
Trace a copy of back and front and adjust the length to 3/4.
Draw the underbust line lowering from bust point as half of bust distance minus 1 or 1,5cm.
Raise shoulder point along shoulder line by 2 to 3cm, then redraw armhole.
Draw the new neckline widening it by 4 to 6cm along shoulder line, then lower 3 to 4cm in center back and draw the deep V in front up to underbust line.