I like the stove idea too if the goal is to heat the whole house. There is the disadvantage of the fireplace being on the end of the house. However, as long as the openings between the DR and Kitch. are left open, I think a fan can help with this. With all sliders left wide open, in the dining room, put a 12" table fan, on the floor, pointing line of sight towards the stove. Run it on low speed. What you are doing is blowing the cold air towards the warm. The cold air will be replaced by the warm air. The dining room may still be a few degrees cooler, but the kitchen should be cozy.