Aonther option is to connect a short invisible wall segment using a 'room divider' wall type perpendicular to the railing. Then reverse the layer direction of one side of the railing. It should create a newel at that junction. Simply center that wall segment in the room, or dimension it for a more specific placement. The newel would be placed without the invisible wall segment, just by reversing the layer direction, but the invisible wall segment gives you a simple 'slide' to move that connectio