A guy turns a guy friend into a woman. Not just any woman, but an exact or near exact copy of his own sister. His friend decides to live as his life looking like his friend's sister for a while. After a while the friend decides to seduce the guy who turned him into a woman. Since the guy had a thing for his sister so he agrees. Before they do anything he tells his friend that pregnancy is a possibility and if that happens there would be no turning back into a guy. The friend is willing. No pregnancy happens though. So the friend us turned back into a guy. So the main guy then turns himself into a woman either a near copy of his sister or a different woman. He/she is getting ready to have sex with his friend but before he does anything with his friend he/she is caught by their own dad and is impregnated by him or his friend or his friend's dad or brother.