The dead space is not due to the foyer. The dead space is created by stair location, and it's just a BAD plan. Your most frequented spaces are squashed .It's just a bad plan dear. The only recourse as is, is to forgo a formal dining space, use the "family room" as all purpose dining, and the"living/dining as a nice large family room living space. In other words...lose the concept of formality and repurpose the spaces.

You have a plan with too many functions in a small foot print.

I agree with the above comments. Your family room is also small. Why do you need two covered porch areas - why not choose a plan where that space is interior?

Change ho you USE the space is the point. The rooms "labels" are just that, with the exception of kitchens baths, and bedrooms.