Resource to use when someone acts on a Patient's behalf

I’m looking at business activities that occur in the pharmacy domain and trying to see how FHIR resources map to some standard business activities.

One scenario that certainly occurs in the pharmacy domain is where someone else acts on behalf of the patient. It could be a parent picking up a child’s prescription, or it could be a more formal healthcare provider scheduling a MedicationDispense or MedicationAdministration.

In terms of recording the interaction between the person acting on behalf of the patient and the pharmacy, is there a FHIR resource that makes sense for this? My initial thinking is that this type of interaction should result in an Encounter resource, and the participant property would be used to record the authorized representative involved in the interaction.

Am I on the right track with this?

Someone who acts on behalf of the patient because of a personal relationship (relative, friend, neighbor, etc.) would be RelatedPerson. Someone who acts based on their profession (physician, cab driver, receptionist) would be a Practitioner. How you would point to those resources would depend on what they’re doing. Resources typically allow choices of these (and possibly other resources) for things like “informer”, “author”, “performer”, etc. If you want to convey an action that isn’t present in a resource, that could be an extension, could be a related Task or could be something else. (Different types of actions could well be modeled differently).