Answer: Based on your description it sounds like the old stones are just set into the soil. I would suggest you pry up the old stones and remove them, then set the new stones in their place. Each stone should have a level layer of sand beneath it and, if necessary to level a stone with an uneven surface, a few dabs of concrete or mortar can help as well. If it is a more extensive project you might want to consult on site with a professional contractor or landscape installer.
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