CARIN BB needs to add a relatedPerson profile that can be referenced in an ExplanationOfBenefit.payee.party, to split out demographics from the Patient resource for when the payee is not a patient and the demographic information known is not at the level of that from US Core Patient. 

This issue is that CARIN BB must use US Core 3.1.1 because of regulatory reasons. US Core 3.1.1 does not have the RelatedPerson profile. Instead we are proposing creating a profile the replicates the constraints (cardinality, MS, and Invariant) of the US Core 5.0.1, with some additional CARIN BB specific requirements (as detailed in FHIR-37740 and currently available here: https://build.fhir.org/ig/HL7/carin-bb/branches/C4BBRelatedPerson/StructureDefinition-C4BB-RelatedPerson.html)