Most patterns sold in the US are multi-sized. In fact, I've never seen a Simplicity pattern that wasn't multi-sized. When you open it up, take a look. Are there multiple sets of cuttings lines for each piece? If so, you're in luck! Here's what you do: examine the pattern and figure out where the waist line is on each piece. It's usually marked, at least on the center back. Extend that waist line all the way out to the edges of the pattern piece.
Now, look at the measurements on the back of the pattern. Compare your waist measurement to the chart. That is the size for your waist. Now look at your bust measurement and figure out our size. Now here's the interesting part: you can use a dressmaker's curve or French curve to join one size's lines to another. For example, if you're a 10 at the waist and a 12 at the bust, start at the waist and merge the 10 cutting line into the 12 cutting line above the waist.
You can do the same thing for the hips: for instance, if you're a 10 at the waist and an 8 at the hips, use the cruve to merge the 10 cutting line into the 8 cutting line below the waist.
For pattern pieces that are entirely below the waist (like the skirts on this pattern), cut whatever size your hip measurement told you to cut. For pattern pieces that are entirely above the waist (like the shoulder ruffle on this pattern), cut whatever size your bust measurement told you to cut.
