FamilyMemberHistory profile needs to have a more constrained binding on Relationship code set

Relationship in Family Member History resource is significant in understanding what preventative or ongoing care should be given to a patient.  However, if the Family Member is not a "blood relative", this can impact the significance of the history.  QI Core lists an "example" binding to a code set that looks adequate to represent the relationships needed but because it is example binding implementers could use other code sets that are less specific.  It is suggested that the binding be changed to at least preferred if not extensible to enhance interoperability.