How are visits attributed to POIs with a parent POI? Are visits counted for both the child and the parent POI?

It depends on whether the parent POI is an enclosing structure or not. Enclosing structure means that the child POI is fully inside the parent POI without its own external entrance. If the parent POI is not enclosing (for example, strip malls and outdoor malls), visits are counted both to the parent POI and to individual stores. For enclosing parent POIs (such as indoor malls, casinos and hotels), visits are only counted toward the parent POI and not the child POI (e.g., the tenants of the indoor mall).