Hello reddit!
I just tried converting a zipper back dress that didn't fit right anymore, to a corset back dress to get more wear out of it. I got a corset back kit off of Amazon (potential mistake number one?), sewed it in ok, just need to finish up the top edges so they look nice. But once I put it on and had it laced up, it looked kinda bad... Here is what I think might be wrong: -The dress itself isn't very structured, so I wondered if adding a piece of boning beside the lacing loops on the inside would help reduce this pulling and bunching up of the fabric. -The loops themselves might be too wide in their spacing, this could also be causing some stretching and bunching. The more loops I have, the better the force distribution, so in theory, less pulling and bunching. -This also shows that the only place that needs extra space is at the top, should I just put in a half zipper or snaps or hooks or something, and half corset back? I think this would be too much so I'm not inclined to do this. Please help me figure this one out, I would love to wear this dress to a fantasy ball in February!

You’re on the right track with your thoughts. Adding some boning next to the lacing strips should really help with the puckering. Below the waist the corset back seems to just be pulling the pleats open. So I think you may still need some extra room in that area to have the pleats fall like they are supposed to. I think that the easiest way to solve this issue would be to do bunny ears lacing (where you tighten the lacing from loops at the waist instead of from the bottom) so you can tighten the top while not adding too much tension to the bottom of the closure.
Realized I might not have explained this super well. TLDR—add boning and look up bunny ears corset lacing.
That was very insightful, thanks for your thoughts! You make a good point with the bunny ear lacing, and that way I could do it up myself too, if I'm thinking of the right thing.
Lacing requires resistance, aka negative ease, which it doesn’t appear to have below the waist seam. So you can either put the zip back as far as the waist and have the corset triangle end there, or, if you want the corset triangle to go all the way down, you can stitch the skirt panels down to the corset panel in the required shape to line up with the top.
Among other considerations, the first method will leave the waist basically its current size and add width mostly at the bust, while the second method will add width at the waist. You can fold the original edge where the zip was under a bit if need be, to create an accurate line for the lacing (and yes, some boning or at least sturdy interfacing would help)
I'd consider adding two bones at each side, and grommets between the two bones. Maybe also add some stiff interfacing at each side. Don't use rigilene bones, but better use plastic boning or flat steel boning.
Agreed-boning would be a huge help here! Either side of the opening. You could consider adding them to your side seams or even to the front of the bodice if sagging is a problem in all parts of the bodice.
Please though, I would not buy expensive boning. Just go find some stiff zip ties from your local hardware store. I have used them frequently in costume/historical clothing and I think for a non daily-wear item they work just amazingly and are so so much cheaper and easier to find! If they end up not being beefy enough you can always buy something more robust later!
I actually have left over boning from a project I did years ago and I'm so jazzed lol!
https://preview.redd.it/idn8yxr6g9ag1.png?width=1080&format=png&auto=webp&s=ddde4c4e35d9553213a8bec469c491f71f80aa68
I had to take the photo myself so it's blurry, but adding boning worked! I added some more to the side seams as well to help structure the dress some more.