To start with you need a whole front, so trace one, flip the paper and trace another one. I then copy over that line from the right side so I have a whole front traced on one side of the paper. I particularly like working with Ottobre patterns because (apart from the great fit) they don't have seam allowances added. (It is a whole lot easier to work on patterns with no seam allowances and add them when you're done.) If you have a pattern with seam allowances already on it, it's worth marking in the stitching lines to make it easier to work with.
You need to trace the shoulder (stitching) line. If you have an envelope neck design this may be marked on. If not, there will be a registration mark to line up the overlap. Use this to work out where the shoulder line is.
I've used KS2433 to illustrate this. I traced the front and back pieces, overlapping them where indicated by the notch. I then folded my paper so that the side seams lined up and creased where that put the shoulder line. I've drawn in a dotted line to mark it. (I haven't subtracted the seam allowances for this, since it's just to illustrate how to find the shoulder line)
As you can see the resulting neckline needs a bit of tweaking, but at this stage that is very easy to do to produce a smooth neckline.
Then you draw the style lines onto the whole front. The neckline in the original pattern I'm using was to be bound, so the neckline here is the finished neck edge. I drew a line from the neck edge to the armhole seam. This line is the new finished neck edge. Now draw another line 1.5cm in from this line. This is the new stitching line for the neckband. The reason I choose set in sleeves becomes apparent here. If you choose a raglan style, the finished neckline will be shorter, which gives you less room to fit over the child's head. It is unlikely to be so much shorter that it causes a problem, but I figure why risk it?
The two parallel lines across the tummy are the cutting line and fold line for the under layer.
Then using a tape measure on it's side measure the finished neckline from centre back to the armhole. The measurement you get is half the length of the finished neckband (since you're measuring half the pattern). Easy!
Cut out your pattern pieces along the new cutting lines. (You'll be working with two separate pieces of paper for front and back of course, not a single piece of paper as I'm showing here since this illustration was just a tracing to show the process.) This gives you new front and back pieces.
Make a neckband pattern piece twice your finished width, plus seam allowances, and half as long as the finished neckband so you can cut it on a fold. My finished neckband is 1.5cm wide, so my pattern piece is (1.5cm + 1cm) x 2 = 6cm wide (finished width + seam allowance) x 2 (since it's folded in half.)
The sleeves are unaltered from the original pattern.
There you go, pattern done! Next up I'll show you how to sew it together. I promise it's easy too.