Creating groups from the target figure indeed can be a vulnerable process, especially when there are folds in the garment in a location where a group cut is made.

One problem with the fitting room and the setup room automatic grouping is they do not show the proposed grouping and then give the user the option  to edit while things are still simple.

PhilC offered a cunning tool named obj2cr2 that assigned facets to a body part group based on the x and y coordinates,  or rather on the color of an area of an image of the figure profile. Problem is of course it requires section location fore and aft to be the same.

This link leads to a script by yours truly attempting to overcome this restriction by using functions cutting the xyz space until the body part for a facet is found, so if facet is below hip-thigh cutting plane but above thigh-shin cutting plane and the x- coordinate is positive then the facet is assigned to the lThigh group.  In practice this works fine also for figures in A-pose. The cutting planes of course are specific for a figure. The linked script is for Project Evolution.