I'm making a cake using black fondant for the top tier. I've never worked with a large amount of black fondant before, and I'm a little worried about the colour staining peoples mouths. Is there any way that the risk of staining could be reduced, or somewhat controlled? I'm using black MMF billows on top of another layer of MMF. (which was going to be black but I'm thinking that another colour may be a better option to reduce staining.)

If its black its going to get on people's mouths no matter what you do. If you put it on really thin that will help, but they'll still have black tongues afterward.