If you are just assigning new material names to individual body parts then another way is to:-- Load the file into UVMapper.

• Edit/select by group and select all the body parts you want to change.
• Now Edit/assign and give them all a new material.
• Save the OBJ with a new name.
• Edit the figure CR2 to point to this new OBJ.

The grouping tool will work, and may be the best way if only sections of a group are required, but I think you will find this method quicker for a body suit.