Order Management Plugin / Accounting assignment

In Order Management Plugin, we'd like to have a field for Accounting Assignment that could be used when printing purchase order. We impose to all our suppliers to clearly indicate on their invoices our accounting assignment so as to ease the job of our accounting departement when resgistering invoices.

Moreover, we would like to be able to specify accounting assignment for each purchase order lines, if needed: a single order with separate lines for software license, software maintenance, hardware, hardware maintenance, system integration service and shipping fees would require as many as sic different accounting assignement (one per line) as those lines obey different accounting rules.

We could also have a single order having lines paid for by a budget and lines paid for by another.

Have such purchase order accounting assignment and purchase order line accounting assignment (default value = PO accounting assignment) would ease up the job of accounting (all the more true if it has been outsourced...)