When multiple places reside at the same location_linkage.landmark_id, at least one place is designated as the primary location (i.e., Parent) based on factors such as in_business status and place_type.
The remaining, non-primary locations (if any) reference the parent infogroup_id in the location_linkage.landmark_id field:
See also:
location_linkage.parent_relationship- Data Dictionary- Location Linkage - Data Guide