I'm a firm believer that Doms should be Doms. That doesn't always meen slapping a sub around. In fact I think that Doms should be far more disciplined than their subs need to be. That being said the role of the sub is to be pleasing to her Master. If hitting your sub is not pleasing to you then don't do it. Of course we all want to give our subs their fantasies and be the fulfilling Master but we are responsible for so much more sometimes.

If it were me I wouldn't slap her around because that's not what pleases me. I would ask her to describe in great detail what mentally it is about that act that she wants. Is it the violence play? you can give her that without slapping her around or is the girl just a pain slut? You can certainly give her that without crossing your comfort.

I find that subs don't always know exactly what they want. They know how they want to feel though. They think they know what act will give them that feeling and that isn't always the case or we can just do better.

Either way she is just going to have to submit to what you want, that's part of her job.