curl --request PUT \
  --url https://api.vantage.sh/v2/managed_accounts/{managed_account_token} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "name": "<string>",
  "contact_email": "<string>",
  "access_credential_tokens": [
    "<string>"
  ],
  "billing_rule_tokens": [
    "<string>"
  ],
  "email_domain": "<string>",
  "msp_billing_profile_token": "<string>",
  "payment_terms_days": 123,
  "include_managed_account_integrations": true,
  "billing_information_attributes": {
    "id": 123,
    "token": "<string>",
    "company_name": "<string>",
    "country_code": "<string>",
    "address_line_1": "<string>",
    "address_line_2": "<string>",
    "city": "<string>",
    "state": "<string>",
    "postal_code": "<string>",
    "billing_email": [
      "<string>"
    ]
  },
  "business_information_attributes": {
    "id": 123,
    "token": "<string>",
    "metadata": {
      "custom_fields": [
        {
          "name": "<string>",
          "value": "<string>"
        }
      ]
    }
  }
}
'

{
  "token": "acct_dd2fdf6564b60319",
  "name": "New Name",
  "contact_email": "newguy@acme.com",
  "parent_account_token": "acct_bb022aecd1125ada",
  "access_credential_tokens": [
    "accss_crdntl_686904ffd39a4618"
  ],
  "billing_rule_tokens": [],
  "email_domain": null
}