For GP's purpose, can face recognition techniques be repurposed for, um, other body parts recognition? Sometimes the actresses are facing away from camera. There are exposed lips, if that helps.
Yes, for actresses _and_ actors I'm sure you'd get the same level of performance as you would for any facial recognition use case. You can't do facial recognition on someone's back, but I'm sure there are other techniques/models that can be applied, many people have unique marks/features etc.