Here is the nice basic Full Bust Adjustment I used on the Tunic Dress.
- Cut out your front pattern piece.
- Mark the apex of the bust (if not already printed on the tissue).
- Draw Line 1 straight up from the hem to the apex then to the stitching line of the arm hole, about 1/3 of the way up. Most patterns have a notch marked about here.
- Draw Line 2 from the center of the bust dart to the apex.
- Draw Line 3 horizontally from Line 1 to the center front.
- Cut up Line 1 from the hem to the armhole but not through it, leaving a hinge. Pivot the spread the side piece to add your desired width (To find out the FBA needed, see this post).
- Cut through Line 2 from the side leaving a hinge at the apex. Swing the side piece down so the cut edges of Line 1 are an even distance apart (2 inches in my case).
- Cut all the way through Line 3 and slide the bottom piece down so it is even with the other side.
- Fill in all the gaps with paper. Redraw the bust dart starting at the original dart legs and ending 2 inches from the apex along Line 2.
You can see when we lie our new piece over the original how length and width has been added. The size of the dart has increased meaning that when it is constructed the length of the side seam and the arm hole remains unchanged.