>>2924141a) Lower the center / groove bone, whichever is not used, to keep the feet on the ground. Use MMM layers or additional bones if both are utilized or offset all their keys at once on Y. This alone can result in hips spreading wider, but it can also result in undesirable rotations.
b) If it's an IK motion, you can use mirrored bone morphs that move leg IKs apart on the X axis. Morphs are easier to control relative to keyframes, and two sets let you keep the legs spread even if the character turns away, while four will allow spreading legs regardless of the X rotation value, but at that point it becomes too autistic.
c) If it's a FK motion, you can either use the make_ik_from_vmd script of PMX-VMD-Scripting-Tools-master or enjoy doing it frame by frame.
d) If your true aim is to make the hips wider, use a bone morph with mirrored X movement and Z rotation on D-bones and find the correct rotation values for hips/knees/ankles (that minimize the shift of the feet from their default positions) through trial and error.
