The Account.guarantor.party can reference a Patient, RelatedPerson and Organization today. This works fine when the guarantor is the patient of the account themselves, or an organization, but it doesn't really work when the guarantor is a person who is not a patient. Let's say for a children's hospital, you have a parent who is the guarantor for their three children who are patients. In FHIR today, this would equate to three different RelatedPersons, but from a guarantor perspective we are talking about a single person. We should be able to use a single guarantor person reference when querying for Accounts by guarantor person. We don't want to use a Patient to represent the parent here, because they are not really a patient of the healthcare system receiving care. I think one solution could be to update the RelatedPerson resource to support relationships to multiple patients making it more representative of a single person instead of having to have duplicates of the same person for each patient they are related to.