Playing with a pattern, Simp 2436

To make a special dress for my Big Girl’s 9th birthday, I made up one of her sketches.  Here are the steps I took to modify this pattern.

I used the line drawing from the pattern instructions to create the look I wanted.  I used Simplicity 2436.  From my Big Girl’s sketches I knew she wanted turquoise and lime green.  I couldn’t find lime green corduroy locally, so we went with a bright pink I’d seen her admire.
I used the pattern instruction sheet, to make sure I had the pattern pieces I would need for the design.  I was adding contrast bands, so I needed to cut a few extra pattern pieces.
To add the contrast band to the sleeve, I chose the point I wanted to split the sleeve.  I chose the lengthen/shorten line to be the seam line between the sleeve and the band.
Because the seam allowances for this pattern are 5/8 inch, I drew a new cutting line 5/8 inch below my new seam line.  When I cut my fabric, I would cut my sleeve along this line.
To draw the pattern piece for the contrast band, I traced the bottom of the sleeve pattern, using my new seam line as the top.
I added a 5/8 inch seam allowance to the top of the seam line of the sleeve band piece.  This is my new cutting line for my sleeve band.
I wanted to add a little length to the dress with my contrast band.  To determine the seam line for the contrast band, I had to do a little math:  I subtracted the seam allowance from the hem allowance.  Then I redrew the bottom cutting line of the dress pattern piece this amount from the original cutting line.  My hem allowance was 1 1/4 inch.  My seam allowance was 5/8 inch.  1 1/4 inch minus 5/8 inch equals 5/8 inch.  So, I drew my new cutting line 5/8 inch above the original cutting line.
To make the pattern piece for the back contrast band, I extended the lines of the pattern.  To determine the length of the band:  5/8 inch seam allowance + 3 inches finished band + 1 1/4 inch hem = 4 7/8 inches.  So my band was 4 7/8 inches long.  I chose to eliminate the center back seam on the band (shown on the right in this picture), so I drew the cutting line in 5/8 inch and marked my piece to CUT ON THE FOLD.
I created my pattern piece for the front contrast band the same way.
I cut all my band pieces and my facing pieces out of my contrast fabric.
After I had all my pattern pieces cut out, I followed the pattern instructions to complete the dress, including the front zippers.  The only exceptions to the instructions are listed below:
Before sewing the sleeve, I stitched the sleeve band onto the sleeve, then I completed the sleeve.
After completing the dress, except for the bottom hem, I stitched the side seams together and the contrast dress band.  Then I stitched the band to the dress, matching side seams and hemmed the band.