No it would be less work, if you implement this feature by allowing the due dates and amounts to be modified on screen. There would be no re-posting of additional transactions, no GL implications, no possible modification of original or current balances.

It's sort of like modifying an AP due date by using Payment Control (easy) rather than adjusting the invoice (hard).

While I am on the subject, clients who need the multiple due date feature also need the ability to display invoices on a statement with four numeric columns - the original amount, the payments/credits applied, the balance due/overdue, and the remaining balance not yet due. There would be no need to show payments/credits separately unless they are unapplied.