@Brucanna there is a link of a sorts, in that Manager shows an inventory transaction view. but there is no actual link to the actual invoice per se as the invoice doesn’t care when the products were bought and what they cost.
Lubos apparently implemented this cost adjustment to fix the issue of Manager not knowing what the purchase price was at the time of sale (if negative inventory). I am not sure why the cost adjustment cannot adjust the table row where the sales invoice is showing in the inventory transactions.
But because its very unlikely that this scenario will happen again, I will just change the dates of the invoices. not proper accounting, but I don’t get audited to that level, so who cares.