Transfer To Balance Account
There are two different ways you can transfer money to a multi-currency balance accounts:
Simply send domestic bank transfer from a bank account to the balance account's bank account details (e.g. IBAN, sort code & account number, etc.). There is no need to set up a quote/transfer in this case.
Create a quote/transfer and then fund that transfer as per requirements.
Next, call Check account balance endpoint and get the recipientId field value from the response.
Note that recipientId does not change so can be stored and reused.
Next, create a transfer. This is the same call as described in the Transfer Create API Reference, however the value for targetAccount should be the recipientId as determined from the previous step.
As per the standard create transfer flow, you also need to create and pass a customerTransactionId for idempotency.
Once the transfer is created, a method will be required to fund the transfer. This will differ based on your specific integration.