Credits

Credits are first declared through the expenses declaration
A GET API allows to retrieve the list of declared credits (see loan applicant data, expenses)
For those being consolidated, a PUT API allows to update the payout instructions of a given credit, based on the id.

Insurance premiums

In the purpose breakdown (purpose split), specific purpose detail id's are reserved for the life insurance premium of the primary and secondary borrower. The se can be declared through a PUT API allowing to provide the list of purpose splits, matching the total requested amount minus the amounts of the loan to be consolidated.
A GET API allows to retrieve the list of purpose splits
For the purpose splits not to be paid out on the borrower bank account, another PUT API allows to provide the payout instructions of a given purpose split (typically an insurance premium to be paid out to the insurer), based on the id

The remainder of the loan amount is paid out to the borrower's bank account, no need to provide the amount, this is computed.
The IBAN to be used can be provided using a PUT API
a GET API allows to retrieve the bank account of the borrower currently attached to the loan application