In this case, when a client creates an Observation entity, the client SHOULD omit the link to a FeatureOfInterest entity in the POST body message and SHOULD not create a related FeatureOfInterest entity with deep insert. And if the service detects that there is no link to a FeatureOfInterest entity in the POST body message that creates an Observation entity, the service SHALL either (1) create a FeatureOfInterest entity by using the location property from the Location of the Thing entity when there is no FeatureOfInterest whose location property is from the Location of the Thing entity or (2) link to the FeatureOfInterest whose location property is from the Location of the Thing entity.
At the moment we are doing (1) all the time.