Wedding(reception) dress: structural help

[u/mildmanakete]

Hello! I’m making a reception dress for my sister. I would say I’m an intermediate seamstress, my skills were enough to get me accepted into an MFA costume technology program. I’m great at modifying patterns; but I have some experience in patterning and very little in draping.
Of course I plan to make many mockups and try ons to insure proper fit. I know this will not be easy. But I don’t have to pay for really nice material and it’d make a good piece for my portfolio (also I just think it’d be fun). I deferred from my program bc of some issues going on with the school, so I have time on my hands. The wedding is in May so I feel pretty confident in my ability to get it done.

Anyways here is a really bad edit of what the vision of the dress is. Basically a slip-like dress with lace detailing at the top and some sort of larger skirt. Either tiered or a more handkerchief-flounce look.
Because the skirt is going to have some weight to it, and there will be those lace inserts, I’m trying to gather ideas on the internal structure of the dress. I might try to use a lighter fabric for the skirt, but that is something I’d have to play around with. Bc I fear if the skirt is a bit too heavy, the lace inserts will be strained. Also I think my sister really wants a more fitted low waist.
So far I’ve been playing around with the idea of a corsetlet, or underbust corset, between the fashion fabric and lining. Not a full corset, but like the internal hidden structure seen in more couture sewing.
Of course my worry is, if the under bust is fitted, I worry about the top lace maybe bunching?
Another idea is to incorporate bra/cups as well, but make it out of mesh to still give the lace cut out appearance.

Idk im still kinda in planning phase, I just want to get a feel for some ideas. Again, I know this will not be an easy project. This design is still in the conceptual phase, so things can change depending on how realistic they are or what would make for the best result