Add or update a child's birthday

POST /customers/{customer_id}/children


Scope	`customers:write`
Customer session token	Accepted with the `write` scope, for the token’s own customer
Rate limit class	`write` (limits)
Idempotency key	Required (idempotency)
MCP tool	`charm_save_customer_child`

For the child birthday rule. A parent’s consent: true is required once; the program’s limits and the once-a-year change lock apply. Refusals carry details.reason (rule_disabled, consent_required, limit_reached, change_locked, invalid_date, name_required, year_required).

Parameters

Name	In	Type	Description
`customer_id`	path	string	Shopify customer GID (percent-encoded, e.g. `gid%3A%2F%2Fshopify%2FCustomer%2F123`) or the numeric customer id.

Request body

Field	Type	Description
`id`	string	Existing entry to rename or re-date; omit to add one. (optional)
`name`	string	(optional)
`birthday`	string	`YYYY-MM-DD`. (optional)
`consent`	boolean	The parent or legal guardian confirms. (optional)
`locale`	string	(optional)

Response `200`

Returns ChildrenResult.

Field	Type	Description
`changed`	boolean
`children`	array of Subject

{
  "changed": true,
  "children": [
    {
      "id": "id",
      "name": "Gold",
      "birthday": "birthday",
      "species": "species",
      "updated_at": "2026-10-01T09:30:00.000Z"
    }
  ]
}

Example

curl -X POST "https://charm.appfleece.app/api/v1/customers/7712345/children" \
  -H "Authorization: Bearer chrm_live_..." \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{}'

Errors

unauthorized · invalid_token · token_expired · insufficient_scope · access_required · not_found · validation_error · rate_limited · idempotency_conflict

Every error body carries code, message, request_id and a doc_url pointing at the matching entry in the error catalog.