Lining sheer illusion panels?

Hi Emma! Have you checked with a seamstress about this? I believe it should be a fairly simple alteration, though a seamstress would be able to give you more information! I would think they'd also have before and after pictures of similar work they've done on other dresses (or at least the after pictures).

It definitely is a simple alteration, but the end result means that the embellishment won't stand out as much as it did when it was unlined.

Here are some pics to give you an idea - you can usually choose how many layers of tulle you'd like to use in building up opacity, so if you don't want full white, you still can get a bit more coverage.

here is a video on how it is done, which I know isn't what you're looking for, but does clearly show what it looks like before and after:

https://www.youtube.com/watch?v=9RbXrqecPJw