You will find somewhere in the cell a few xmarkers that are enabling parents of all the additions. The quest responsible for buying your home upgrades (in most likely a fragment) will enable those xmarkers and hence make all your furniture appear. For your editing purposes only, enable those xmarkers and you should be able to see all the furniture in-game, now please DON'T delete any of the stuff you don't want. For each piece you don't want go along to it's enable tab and clear the controling xmarker this should make it so that it will never get enabled, then just grab it and move it outside of the visible room.