I recently had two 15k cold weather rated heat pumps installed on each side of a  side by side duplex. The single head is in a small 10 x 10 kitchen with a single doorway leading to the living room. The kitchen gets very hot if we set the heat pump to 80 it will get up to that temperature but the adjacent dining room is barely getting up to 65 degrees.  The dining room also has the stairway to the upstairs. We have done a lot of air sealing in the attic and plan to bring it from 3″ of loose mineral wool to R-60 with cellulose, which should help a bunch. Regardless, I’m still concerned as the weather is much more mild right now and there are still cold spots in the home. 

We did a manual J on the building and this heat pump is sized appropriately. 

I know there has been prior discussion on these forums that transfer fans don’t work that well because the delta T is not great enough and/or the cfm are too low.  Usually the discussion talks about HRV type fans or bathroom fans. 

I still need to try to minimize the use of backup heat in this home. I’m thinking about the following options:
-Get a large whole house fan in the wall blowing air from the kitchen to the dining room. I’ve looked into fans that can move 1,000 to 2,000 cfm. 
-Open the area on top of the doorway and somehow box it in to look like an open window.
-open up the top half of the wall (kitchen sink is on the lower half of the wall between the two rooms).
-Cut a hole in the ceiling of the kitchen to act as a cold air return from upstairs to complete the conductive loop.

I don’t want to buy another mini split. I just want to maximize what is there and minimize the electric resistance heaters.