curl --request POST \
  --url https://app.yampi.ai/api/v1/accounts/{account_id}/conversations/{conversation_id}/group_contacts \
  --header 'Content-Type: application/json' \
  --header 'api_access_token: <api-key>' \
  --data '
{
  "contact_ids": [
    123
  ]
}
'

const options = {
  method: 'POST',
  headers: {api_access_token: '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({contact_ids: [123]})
};

fetch('https://app.yampi.ai/api/v1/accounts/{account_id}/conversations/{conversation_id}/group_contacts', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://app.yampi.ai/api/v1/accounts/{account_id}/conversations/{conversation_id}/group_contacts"

payload = { "contact_ids": [123] }
headers = {
    "api_access_token": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

{}

{
  "description": "<string>",
  "errors": [
    {
      "field": "<string>",
      "message": "<string>",
      "code": "<string>"
    }
  ]
}

{}

{}