Alright. Here's the file. Out of respect to the author, I did not include the textures, but just the base geometry. Once you have it installed, load the Victoria 3 base and then navigate to Figures > HF-Rebel Line and it should load just fine. Conform the dress to the Victoria 3 base and you'll see that it follows thigh movements just fine, despite the entire skirt area being defined as a single Hip group.