I have a 3 pulley system statically balanced hanging weights at a determined relative angle (we are taking into account friction). If I change the position of one pulley, angles will remain the same. However, if I have a 4 pulley system, at the same conditions, changing one's position will affect the relatives angles between them all. I would like to know why that happen. Why, with 3 pulleys, changing one's position will not affect their relatives angles and not with 4 pulleys?