>>3014272You deal more either with the bends or the panties clipping through legs opposite to the rotation angle, that's about the amount of weight you give the パンツX足 bones. The former is definitely preferable. (By the way, not having the left/right indicators at the start of the name will prevent you from being able to utilize the easy flip/mirror offset/weight functions.) You can try the double-IK setup for a slightly different behavior:
https://litter.catbox.moe/ftl8eri5zhpg4ciy.pmx 