To parent the dress to  La Femme, 

1) With both dress and La Femme in default position, select the dress.

2) Assuming it is a prop, choose Object > Change Parent.

3) In the dialog that appears, select La Femme's HIP as the parent.

In regards to the bench being a CR2, are you saying you are not able to uncheck the Goal: Center of Mass objects, and leave only the body part named "prop" in there?