Not 100 % of the name i pressed, but I cant see the effect it does, nothing can be moved around or be swapped out, its on the bottom of my list after if inished my main house part. anyone know what it does?

I think it allows you to turn your original small house into the entrance hall for your big house. It changes what Items can be selected from the carpenter's workbench

Does it? I was scared incase it got rid of all the extra wings and main hall, if thats the case then halleluja, i hate the hall, cause it doesnt have fall furniture, however if i need to re-build furniture thats a few of my recourses gone down the drain

you lose the stuff in the main hall if you do this ?

No you only lose the stuff in the original small house, it has no effect on the main hall.