A collective of robots can together complete a task that is beyond the capabilities of any of its individual robots. One property of a robotic collective that allows it to complete such a task is the shape of the collective. One method to form that shape is to form it at a size proportional to the number of robots in that collective, i.e. scalably. In our previous work, scalably forming the shape of the collective required that each robot know the total number of robots in the collective. In this work we present a method called S-DASH, which now allows a collective to scalably form a shape without knowing how many robots are in the collective. Furthermore, S-DASH will change the size of the shape to reflect the addition or removal of robots from the collective. This paper also provides demonstrations of SDASH running on a simulated collective of robots.