How can we edit distribution fields in accounts payable for One time payments related to projects?

When making a one time payment, we have had problems ensuring that it is posted to the projects module. We use the spreadsheet loader, and then add the poeta details to the screens afterwards. The problem we are having is that it needs to be added to the manage distributions screens, but these are not editable. We can delete the row and add a new one, but with thousands of payments this is very time consuming. Does anyone know of a way to make these screens editable to avoid having to delete the whole row?