Hey mates, today I'll be showing you how I would do a full bust adjustment on the Rundle Dress. This pattern has a centre front seam with the darts positioned on the inside of the bust.
I have tested a few different ways to do a FBA on this dart position and I actually found it easiest to swing the centre dart to the side seam, do the FBA as you usually would, then swing the dart back around to the centre!
Do you need a Full Bust Adjustment?
There are a few ways to tell if you need to do an FBA. If your full bust measurement is larger than the full bust measurement that corresponds to your high bust measurement in the size chart. Also, if you've sewn a toile and there is tightness in the bust, the fabric is pulling forward at the front armhole, or there are drags lines radiating out from the bust.
The combined C/D cup has a 3.5in (9cm) difference between the high bust measurement and full bust measurement.
If you have determined you definitely need the FBA, you'll also need to calculate how much to add to your FBA.
First things first, find your size in the size chart using your high bust measurement.
Check the corresponding full bust measurements of that size. Calculate the difference between the largest full bust size available in your size and your actual full bust size.
Because the front pattern piece is based on half your body, you will need to divide the number by two – that’s how much you'll be adding to the pattern piece.
For example: These measurements below put the wearer in a size D, except for the full bust, which is an F. There is an extra 4in (10cm) between the full bust measurement for size D and size F. Half that is 2in (5cm). So they'd be cutting out size D and doing a FBA of 2in (5cm).
I'm going to show you how to do the FBA on View B. View A and View B have the same bodice shape, except that View B has a slightly thicker straps! The process will apply to both views.
Prepping the pattern.
You will need your Top Front pattern piece for this adjustment.
Cut away your 1cm (3/8in) seam allowance from the pattern piece. (This is already marked in a light grey line on your pattern.)
Rotating the bust dart.
(For better visibility, the following diagrams will be illustrated using a black line instead of the pale grey line).
Mark your bust point on the pattern piece (shown in red) - this should be roughly 2.5cm away from the end of the dart point. Redraw the dart so it meets the bust point (blue line) and trim the excess away.
Draw a line from the bust point to the side seam (green line). Cut along this line, leaving a small hinge point at the bust point.
Pivot the upper half of your pattern piece, using the bust point hinge, to close up the centre front dart. This will open up a dart on the side seam!
Now we're ready to do the FBA.
Doing the bust adjustment:
Draw two lines on your pattern.
Line 1 (orange) goes from bust point to the underarm
Line 2 goes from the bust point down to the waist.
Cut from line 2, up to the underarm of line 1, leaving a small paper hinge at the bust point and at the underarm.
These hinges will act as pivot points.
Time to add your FBA amount to the pattern. In my example, there was a 10cm difference that I needed to add. But because we're working with a pattern piece that is half of the front bodice, the 10cm is divided in half - to make 5cm.
Place the pattern on a sheet of paper. Tape the section marked (A) onto the paper.
Keeping the hinge points intact, spread the sections marked B and C open the amount of your FBA.
Draw another line through section A (green) and cut along this line. Slide the lower portion of this down to meet section C.
Trace around your new pattern shape (orange line), filling in the gaps. Cut it out.
Now that the FBA is done, we can rotate the side dart back to it's original centre front position. You may want to hold the pattern piece up to your body at this point and check that the bust point is in the right position, or re-mark as necessary.
The red dot in this image shows the bust point, and you may notice it's now lower than the original pattern. Draw a perpendicular line from the bust point, to the centre front (blue line). Cut along this line.
Using the bust point as a pivot point, swing the top of your bodice down to close up the side dart. 
This will open up your centre front dart again! But we need to re-draw the dart so the apex of the dart isn't hitting the bust point and giving us the ol' pointy tit.
At this point, the pattern is looking pretty cut up, so grab a fresh piece of paper and trace on the outline of the pattern. Move the apex of your dart about 2.5cm - 3cm (1in - 1 1/4in) in from the bust point (or more, if your FBA was fairly large). Shown in pink. Make sure that the legs of your new dart are the same length.
Add your 1cm (3/8in) seam allowance back onto the pattern (black line). Cut out your new pattern piece, adding back in the grainline and other important markings.
As always, I recommend making a toile for your newly modified pattern!
Hope this helps
x Lauren