curl --request POST \
  --url https://api.syntage.com/entities/{entityId}/shareholders \
  --header 'Content-Type: application/json' \
  --header 'X-API-Key: <api-key>' \
  --data '{
  "relationType": "shareholders",
  "name": "JUAN MANUEL PEREZ GONZALEZ",
  "rfc": "PEIC211118IS0",
  "shares": 1500.5
}'

{
  "@id": "/shareholders/91ab5678-1234-5678-9abc-def012345678",
  "@type": "Shareholder",
  "id": "91ab5678-1234-5678-9abc-def012345678",
  "name": "JUAN MANUEL PEREZ GONZALEZ",
  "type": "physical",
  "rfc": "PEIC211118IS0",
  "relations": [
    {
      "@id": "/shareholders/91ab5678-1234-5678-9abc-def012345678/relations/82cd9012-3456-7890-abcd-ef1234567890",
      "@type": "ShareholderRelation",
      "id": "82cd9012-3456-7890-abcd-ef1234567890",
      "link": "/entities/91ab5678-1234-5678-9abc-def012345678",
      "shareholder": {},
      "relationType": "shareholders",
      "sources": [
        {
          "@id": "/shareholders/91ab5678-1234-5678-9abc-def012345678/relations/82cd9012-3456-7890-abcd-ef1234567890/sources/73de0123-4567-8901-bcde-f23456789012",
          "@type": "ShareholderRelationsSource",
          "id": "73de0123-4567-8901-bcde-f23456789012",
          "relation": {},
          "shareholder": {},
          "sourceName": "manual",
          "sourceId": "64ef1234-5678-9012-cdef-345678901234",
          "shares": 1500.5,
          "createdAt": "2020-01-01T12:15:00.000Z",
          "updatedAt": "2020-01-01T12:15:00.000Z"
        }
      ],
      "shares": 1500.5,
      "totalShares": 10000,
      "ownership": 0.15,
      "createdAt": "2020-01-01T12:15:00.000Z",
      "updatedAt": "2020-01-01T12:15:00.000Z"
    }
  ],
  "entity": "/entities/91ab5678-1234-5678-9abc-def012345678",
  "createdAt": "2020-01-01T12:15:00.000Z",
  "updatedAt": "2020-01-01T12:15:00.000Z"
}