No one made this yet, so I did. It's surprisingly easy!
Toggles for the flower and/or sleeves of the Summertide Formal Dress for every race and gender.
How to add them to your upscales:
Go to Advanced Editing > Models and select the model you would like to add toggles to (listed in green if you are currently using it)
Every odd mesh (with "atr_hij") is a body one and can be ignored, every even one is the dress.
The flower is the one with the attribute "atr_tv_a", while the sleeves have both "atr_ude" and "atr_tv_a".
Rename the sleeves' "atr_tv_a" to "atr_tv_b"
Press "Save to File" under the path selection.
In the mod with your now edited model, go to the "Edit Mod" tab.
Scroll down to the group creation: fill with a name, set the dropdowns to "Equipment" with ID 6226 and "Body" with ID 1.
Press "Add IMC Group."
Scroll down to the newly added group, and add option "No Flower" (which will turn parts with attribute "atr_tv_a" off).
Also add "No Sleeve" (which will turn parts with "atr_tv_b" off).
It's that easy.