When an AuditEvent is attributed to many .agent values, and there is an obvious relationship (one Practitoner, one Organization) the relationship is implied to be clear. But when there are many this is not as clear. Use-case is where an AuditEvent is by two Practitoners each working on behalf of different Organizations. 

Possible Solutions:
1. Provenance has an agent.onbehalf to address this. Moving to this would make the models similar.

2. Could just indicate that PractionerRole should be used (which might be a contained instance when that is appropriate)

3. Could add an agent.agent so that one agent can be related to another agent. (Like AuditEvent has for entity->agent.

4. This could be considered not core, and an extension used. This extension could be created in FHIR core so that it is available consistently.

Need discussion