Technically, if you use DFDM (data file display and maintenance) you can change non-financial items on the invoice and then print them once they are posted.

I specifically say non-financial items (like comment text) because you don't want to change anything that impacts your general ledger or inventory (such as changing prices or part numbers).

I've had to do this to change a PO number when the customer would not accept the invoice without a valid PO number.

Technically, if you use DFDM (data file display and maintenance) you can change non-financial items on the invoice and then print them once they are posted.

I specifically say non-financial items (like comment text) because you don't want to change anything that impacts your general ledger or inventory (such as changing prices or part numbers).

I've had to do this to change a PO number when the customer would not accept the invoice without a valid PO number.

If you "adjust" an item number using DFDM, you are going to have to modify a lot of files that are updated when the Sales Journal is posted.  You may be able to print a correct invoice, but all of your other historical/summary reports are going to be wrong unless you use DFDM to fix all of the records that are written to when invoices are updated.

I limit DFDM to when there is data corruption.  If things are really wrong, it is SOOOO much easier to post a CM then re-invoice.  Plus the audit trail is maintained for the transactions.