How to restrict users editing the Due Date from payables invoice Manage installments?

We have a situation reported from business where AP users are altering the Payment Terms, Terms Date and lastly the Due Date from Manage Installments. To achieve this requirement, we have frozen the Payment Terms and Terms Date through Sandbox Pgae Composer customizations. However, we cannot do the same for the Due Date available from Manage Installments, due to the reason that the Manage Installments opens up as a Popup window. The selection tools of Sandbox are available behind this popup and doesn't allow us to click on them.

The other way that we have tried opening the invoice from Manage Invoice. Once the Invoice opens from search of Manage Invoice, it is available as a view window. We will have the links available of Approval, Manage Installments, Payments. We have accessed the Manage installments through sandbox from this page. However the Properties of Due Date are different where we cannot get the expression worked for the users, which ideally worked for Payment Terms and Terms Date.