Between R4 and R5, the value set bound to relatedPerson.relationship shrank from 100+ to only 18 codes. What's mostly gone is all the familial relationships.

On the one hand, it's only a Preferred binding so we can use anything we want. But on the other, I think these family relationships are so central to the use cases for this element that they should be represented if only for the purpose of illustrating the intent for that kind of relationship to be coded in this element.

Based on a Zulip chat (https://chat.fhir.org/#narrow/stream/179166-implementers/topic/RelatedPerson.2Erelationship.20value.20set.20shrinkage),  I understand that the WG can't cater for every possible use case. But including at least a core set of family relationships in this value set signals more clearly that this is an important use of the element. Further, these family relationships are universal in ways that some of the included legal-administrative codes may not be (for example, the nuances of different Power of Attorney types are likely to differ across jurisdictions).