Late to this and haven’t read all
the comments but how about tulle over the lace, something like this

When I walked past this today, I had to think of you—a whole store of buttons and fasteners!

We used to have a darling little shop that sold only buttons and decorative braid. How I wish it was still in existence.

If you’re anywhere near Pacific Fabrics, they have the best selection of interesting buttons. Otherwise you’re stuck with Joann’s which has a decent selection of basics.

I haven't read all of the replies, so someone may have suggested this - but I would try stalking this same dress on eBay or Poshmark - regardless of size.

Take all of *that* lace and lining material, and use that for a new, extended under-slip.

WOW. You guys are CREATIVE

I've bought great little navy buttons to add to the black and cream blouse.

One other thought, going on an already-suggested idea, is to use this dress to build another dress in a tonal or contrasting color. Are you familiar with designer Byron Lars? I'm kind of obsessed with him. I've owned two tops by him, and the construction is impeccable - like an opera costume.

His dresses are beautiful to behold - he layers and pieces together all these beautiful textiles, into fashion art.

This kind of idea might be something to try with your dress.

#1 Vegan Leather & Lace Duet

#2 Pieced Brocade Sheath. I tried this on at Anthropologie 5-6 years ago (I forget), and LOVED it. I toyed with the idea of buying it as my One Dress To Rule Them All for parties, holiday events, concerts & shows, and weddings... but I couldn't quite commit. It was on clearance, for around $350, which was a little outside my comfort level, for one dress.

This dress pops up on resale sites frequently, but never in my size.

#3-4 The Alpine Rose dress... this dress is a dream item for me. Something about all those roses and embroidery just ticks off all the boxes for me. (I think it's the Old Italian Lady Of My Soul, the one that loves black lace veils, and ponders putting down plastic covers on the fabric upholstery.)

I think this could be a fun and entirely fresh way of repurposing your dress.

If you do tulle, make sure it's soft. I've worn my share of itchy tulle and it's a drag. My mom used to dye tulle so that might be worth a try if you can't find the color you want in the shop/online. I like this idea very much.

If you're still contemplating a lace solution you might also try ebay - there is the identical dress that you could use for spare lace. It's pricey but that's what make an offer is for Anyway, good luck.

Mary Beth, those dresses are all kinds of wonderful.

To piggyback on Brie's suggestion... even if there isn't an "or best offer" option, sometimes I've contacted a seller, or been contacted by a potential buyer, and usually the transaction ends in the seller accepting an offer

I haven’t read the other comments, so maybe these suggestions have already been made:
Joanne’s or any store that sells fabric will have the buttons. Just make sure to measure one of the old buttons (or take one of them with you) so you know what size to get.
There are companies like https://myslipsshowing.com/ that sell slips that are supposed to show below the hem of a dress, so that might work.

Ha! That’s a good link, Karie!

Thank you all soooo much! I will keep you posted on the projects