curl --request POST \
  --url http://localhost:8080/mrns \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "benefit_provider_id": "<string>",
  "dependant_id": "<string>",
  "external_mrn": "<unknown>"
}
'

{
  "benefit_provider_id": "<string>",
  "created_at": "<string>",
  "dependant_id": "<string>",
  "external_mrn": "<unknown>",
  "id": "<string>",
  "last_modified_at": "<string>",
  "primary_user_id": "<string>",
  "status": "active"
}