This code system http://hl7.org/fhir/relationship defines the following codes:

CodeDisplayDefinition
1 SelfThe patient is the subscriber (policy holder)
2 SpouseThe patient is the spouse or equivalent of the subscriber (policy holder)
3 ChildThe patient is the child of the subscriber (policy holder)
4 Common Law SpouseThe patient is the common law spouse of the subscriber (policy holder)
5 OtherThe patient has some other relationship, such as parent, to the subscriber (policy holder)
<status value="draft"/><experimental value="true"/><publisher value="FHIR Project team"/><contact><telecom><system value="url"/><value value="http://hl7.org/fhir"/></telecom></contact><description value="This value set includes the Patient to subscriber relationship codes."/><jurisdiction><coding><system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/><code value="001"/><display value="World"/></coding></jurisdiction><copyright value="This is an example set."/><caseSensitive value="true"/><valueSet value="http://hl7.org/fhir/ValueSet/relationship"/><content value="complete"/><concept><code value="1"/><display value="Self"/><definition value="The patient is the subscriber (policy holder)"/></concept><concept><code value="2"/><display value="Spouse"/><definition value="The patient is the spouse or equivalent of the subscriber (policy holder)"/></concept><concept><code value="3"/><display value="Child"/><definition value="The patient is the child of the subscriber (policy holder)"/></concept><concept><code value="4"/><display value="Common Law Spouse"/><definition value="The patient is the common law spouse of the subscriber (policy holder)"/></concept><concept><code value="5"/><display value="Other"/><definition value="The patient has some other relationship, such as parent, to the subscriber (policy holder)"/></concept></CodeSystem>