BMI with links to Height and Weight

{
  "resourceType" : "Observation",
  "id" : "bmi-using-related",
  "text" : {
    "status" : "generated",
    "div" : "<div xmlns=\"http://www.w3.org/1999/xhtml\"><p><b>Generated Narrative: Observation</b><a name=\"bmi-using-related\"> </a></p><div style=\"display: inline-block; background-color: #d9e0e7; padding: 6px; margin: 4px; border: 1px solid #8da1b4; border-radius: 5px; line-height: 60%\"><p style=\"margin-bottom: 0px\">Resource Observation &quot;bmi-using-related&quot; </p></div><p><b>status</b>: <span title=\"  ======== need to fix vitals to removed fixed value 'has-member' ==========\n\t&lt;meta&gt;\n\t\t&lt;profile value=&quot;http://hl7.org/fhir/StructureDefinition/vitalsigns&quot;/&gt;\n\t&lt;/meta&gt;\n     \">final</span></p><p><b>category</b>: Vital Signs <span style=\"background: LightGoldenRodYellow; margin: 4px; border: 1px solid khaki\"> (<a href=\"http://terminology.hl7.org/5.1.0/CodeSystem-observation-category.html\">Observation Category Codes</a>#vital-signs)</span></p><p><b>code</b>: BMI <span style=\"background: LightGoldenRodYellow; margin: 4px; border: 1px solid khaki\"> (<a href=\"https://loinc.org/\">LOINC</a>#39156-5 &quot;Body mass index (BMI) [Ratio]&quot;)</span></p><p><b>subject</b>: <a href=\"patient-example.html\">Patient/example</a> &quot;Peter CHALMERS&quot;</p><p><b>effective</b>: 1999-07-02</p><p><b>value</b>: 16.2 kg/m2<span style=\"background: LightGoldenRodYellow\"> (Details: UCUM code kg/m2 = 'kg/m2')</span></p><p><b>derivedFrom</b>: </p><ul><li><a href=\"broken-link.html\">Observation/bodyheight: Body Height</a></li><li><a href=\"observation-example.html\">Observation/example: Body Weight</a></li></ul></div>"
  },
  "status" : "final",
  "category" : [{
    "coding" : [{
      "system" : "http://terminology.hl7.org/CodeSystem/observation-category",
      "code" : "vital-signs",
      "display" : "Vital Signs"
    }],
    "text" : "Vital Signs"
  }],
  "code" : {
    "coding" : [{
      "system" : "http://loinc.org",
      "code" : "39156-5",
      "display" : "Body mass index (BMI) [Ratio]"
    }],
    "text" : "BMI"
  },
  "subject" : {
    "reference" : "Patient/example"
  },
  "effectiveDateTime" : "1999-07-02",
  "valueQuantity" : {
    "value" : 16.2,
    "unit" : "kg/m2",
    "system" : "http://unitsofmeasure.org",
    "code" : "kg/m2"
  },
  "derivedFrom" : [{
    "reference" : "Observation/bodyheight",
    "display" : "Body Height"
  },
  {
    "reference" : "Observation/example",
    "display" : "Body Weight"
  }]
}