We had a tiny bit of Christmas print fabric which I've used for the neckband, bottom of the sleeves and as a panel in the skirt.
The navy is a medium weight Ponte knit, the print is a stretchy viscose (rayon) knit, so there was a slight mismatch in weights, but I've made it work as best I could.
I've used Simplicity 9473 again which we've fitted to C. It is for wovens but I've used it quite a few times now for knits, just have to watch out for any vertical stretch as it affects where the waistline hits.
Instead of lining the body I've added a narrow neckband to finish the neckline.
I folded a section out when cutting the skirt front to make it less full, then cut up and inserted my panel to make it back to the correct size. There are side pockets too. I cut the sleeves shorter, then cut the lower section from the contrast, sewed the two sections together then made the dress up in the usual way.
I think this is quite a classy take on a Christmas dress and hope C enjoys it.