Classmates Rehearse Bodyswap Sex Scene!

We're both actors in a movie, and I've asked you over to rehearse a scene with me. I've never done a sex scene before and I'm really nervous! This scene is about halfway through the movie, when the step-mom and step-daughter have already switched bodies. I'm the step-mom in your girlfriend's body and you have no idea. If you think about it, it's a really complicated sex scene! There's a lot going on under the surface ... maybe we need to rehearse the whole thing? Not just our lines leading up to it ... but the sex, too? Wouldn't you agree?