First I have to pull out my working patterns.
The bottom line DOES go below the line of the original pattern by about 3/4 of an inch for the size 10.
You are going to have to take ratios to estimate how much needs to be added for your size.
Seam allowance needs to be added along the neckline of the front and back, because the lace outer bodice for the beige dress is finished with a narrow hem with very narrow trim added. The hem all around the lace outer skirt is finished the same way. You will have to measure all those edges to know how much edging trim to buy.
And, the foundation bodice and basic skirt are exactly the same for all the dresses.
If this isn't clear, or you need more information, please leave comments. I will answer any questions. I'm sure that will be useful for other's as well.