post
https://sandcaas.undostres.com.mx/wallet/v1/composite-balance/parent//child
Creates a new child balance under an existing parent balance by allocating a portion of the parent's available credit.
The specified credit line (in Mexican cents) is immediately deducted from the parent’s available credit, and both balances are updated atomically to ensure consistency. The parent_id in the path is the external ID (UUID format), not the internal database ID.
The child balance becomes available for transactions as soon as it is created.