Did you know that it's super easy to put the Danica neckline on the Sugar Pea, or vice versa? The two patterns have identical armscyes and chest circumference, so you can simply line them up and trace one neckline onto the other piece!
In the picture below, you can see that I traced the Sugar Pea front onto my fabric (minus the neckline - just the armscye/side/bottom), and then laid the Danica lining piece (for the collared version - if doing another version you can use the main piece instead of the lining) on top, matching up the armscyes, and traced the neckline. Repeat this process for the back piece, and if you are using the lining (for a collared Danica) cut it as usual using the regular Danica pieces.
From there, I sewed the top as per the Danica instructions, using the burrito roll hack (see Kristy's blog post at https://buttonsandbibs.wordpress.com/2018/05/30/the-fully-lined-sleeveless-bodice-burrito-method/) to eliminate the need for armbands.
The only modification I made was trimming the bottom of the lining to match the Sugar Pea back/sides, before moving on to attach the Sugar Pea skirts. In the larger sizes, this would be unnecessary as the lining should be a bit shorter than the waistline and can hang free inside the tunic/dress, as it does with a regular Danica.
The skirts for the Sugar Pea can be sewn exactly like usual, and voila!
Beautiful mash up! Thanks for sharing the details.