See comments for our thoughts on how to represent your use case, but in terms of actual spec changes, we do want to update our Boundaries and Relationships section to include guidance on OrganizationAffiliation:   The Organization resource is used for collections of people that have come together to achieve an objective. The  Group  resource is used to identify a collection of people (or animals, devices, etc.) that are gathered for the purpose of analysis or acting upon, but are not expected to act themselves. The Organization resource often exists as a hierarchy of organization resources, using the  part-of  property to provide the association of the child to its parent organization. This organizational hierarchy helps communicate the conceptual structure, whereas the Location resource provides the physical representation of the hierarchy. The linkage between Organization and Location is from each point in the location hierarchy to the appropriate level in the Organization hierarchy. These links don't all have to be to the top level Organization. When populating the organization and location hierarchies there is often not a clear distinction between these 2, however to assist in making the decision, Locations are always used for recording where a service occurs, and hence where encounters and observations are associated. The Organization property on these resources might not be the location where the service took place. OrganizationAffiliation allows you to specify details about organization affiliations that are more complex than simple partOf relationships, such as organizations that are separate legal entities, or have other non-hierarchical relationships.  No ownership is implied via OrganizationAffiliation .  A single OrganizationAffiliation represents the details of a single relationship between a single pair of Organizations, including the period during which the relationship is active.  Current network members can be discovered by searching for OrganizationAffiliations, and historic data can be retained without overhead and still be accessible when searching.