More thought an modeling is needed to accurately depict a household before you can get the concepts right about modeling a household member's work.  The concept Household member role.  The household member's role seems to be relative to who is the head of the household.  (The patient isn't going to be the head of a household. Every member of a household may or may not be a patient. You need a "fixed" head of household in order to get the household member's role right.  Consider the notion of the Group.managingEntity in FHIR.  You need to fix the head of the household, then the other member relationships will make sense.  It doesn't make sense to define the member role using the relationship to the patient.