When you've set up a transaction to use Multiple Due Dates, the value of each payment is calculated as the total gross value of the transaction less any deposit divided by the number of payments.
When the sum of the values of all the payments plus the deposit is calculated, the result may be different to the total gross value of the transaction. In this case, any difference is absorbed by the last payment.
Any adjustment you make to the amount of any payment, results in an automatic adjustment by the system to each of the subsequent payment. The last payment can't be adjusted.
When an allocation is made, the due value for the payments is reduced. The amount allocated against the transaction is deducted from the amount due until it reaches zero, beginning with the deposit value and then against each payment in date order.
