This is probably worth a try. Make sure IK is turned off, then use "Zero Figure" in the joint editor, then check the BODY and hip tanslations are zero. Export the hip as an obj file, from the menu bar; File > Export > Wavefront OBJ, in the export options use only "As Morph Target".

Now load the obj as a morph target. From the menu bar; Object > Load Morph Target.

If you morphed the thighs and abdomen, you would need to repeate the procedure for those parts too, saving each actor as a seperate morph target. The aim of this procedure is to remove any influence of joint rotations, JCM, etc,  from the morph.