Correcting posted Invoice accounting?

Several dozen AP Invoices related to (non-sponsored) Projects were paid and posted to the wrong Account because incorrect Project information was entered. We now need to correct the GL as well as the Project Costing and AP subledgers.

Each of the Invoices was associated with a different PO -- about half of which are now closed. All of the accounting is correct, however the Project information it was derived from is not and needs to be changed which, in turn, will produce the expected accounting (i.e. there's nothing wrong with our Accounting Rules).

Based on previous guidance from support, we've attempted to