I am rebuilding a 20 year old pond with flagstone edging on the sides. I tore up most of it, but they want to keep half and add the broken peices to create a new pathway to the old. I have limited experience with hardscapes and flagstone. I always thought everyone put a layer of sand down, tamped it and set stone on it. What the original installer did was lay down a layer of 3" mortar, set the stone down and looks like they motared the joints. Can I lay it down using sand and then somehow motor joints to make it look like the old stuff? Any thoughts?