Is it right for a father to sleep with his 16yr old daughter?????

This sounds exactly like a movie I Just watched. No it is not right and in the end of that movie the dad get killed by the daughter because she realized how screwed up it was. That is horrible and you should say something. If your mother already knows and isn't doing anything about it.. then leave. Don't put yourself in a place like that. Next it will be you he is sneaking in to bed with.