Sage Accounting UKI

The reference field on the quote and invoice on Sage BCA is not long enough to give a decent description sometimes. Also, when I prepare a quote, I usually put my customers' PO numbers in the reference box meaning the brief description I entered needs…

Is there a way I can record a customer PO number for an order so it carries over to Invoice, Credit Note, Statement, etc? Some customers are very strict on their PO numbers.