### Move a subscriber to another owner

`POST /api/v1/users/{id}/change-parent`

Re-points the subscriber at a different owning manager. The destination must be a manager the caller may act on, because the owner is both the creditor on a debt and the revenue attribution. Naturally idempotent, so request_id is accepted for your own tracing but is not enforced.

- Authentication: manager session (JWT) or API token
- Permission: `prm_users_change_parent` (Change user parent)
- Risk: danger
- Rate limit bucket: `t_mutate`

#### Parameters

| Name | In | Type | Required | Description |
| --- | --- | --- | --- | --- |
| `id` | path | integer | yes | Subscriber id. |
| `parent_id` | body | integer | yes | The new owning manager. |

#### Errors

| Code | Status | When |
| --- | --- | --- |
| `ERR_VALIDATION` | 400 | parent_id missing or not a manager in this tenant |
| `ERR_NOT_FOUND` | 404 | the subscriber or the destination manager is outside the caller's subtree |