Do you have an example of what kind of data you want to add? There are a few categories. 1) Identifiers from other systems should follow this pattern https://www.medplum.com/docs/fhir-basics#identifiers-naming-resources 2) Putting patients in a Group can be useful if you want to (for example) have a group of patients that all have the same insurance plan https://www.medplum.com/docs/api/fhir/resources/group 3) Extension can be useful for some use cases - the US Core Patient Profile (linked here https://www.medplum.com/docs/api/fhir/resources/patient) for example has a few standard extensions

Thanks for the response. The immediate need for Patient is SSN and Preferred Pronoun. Which maybe identifiers makes sense for SSN but not pronoun. For RelatedPerson, we need the relationship between the patient (sister, spouse, etc)

For the relationship, you can use the RelatedPerson.relationship https://www.medplum.com/docs/fhir-datastore/family-relationships

Yep, thanks, Missed the relationship property on RelatedPerson

There's a preferred valueset here: https://hl7.org/fhir/valueset-relatedperson-relationshiptype.html

For pronoun there is a US Core Gender Identity profile which may be useful for maintaining standards compliance and is extensible in some respects http://hl7.org/fhir/us/core/StructureDefinition-us-core-genderIdentity.html