I'd like to suggest that you shoot a scene where the girls are wearing leather clothing....not the S&M kind of stuff.  But perhaps leather jeans, or leather jackets with denim jeans, and/or leather mini skirts....but not with the girls wearing the same things, mix it up between them.  Leather can be used to enhance the erotic quality of a scene without the need for any BDSM at all.  Just a very sensual element.