Using sage 50 premium accounting. 

I recently started at a place that has their inventory listed in sage.  It is our year end now, and I can't make inventory adjustments to actual because:

When their inventory items were originally entered, they entered them as a $0 cost (through payables) to the company, as they had already had everything on hand from previous years, and were previously reconciling their inventory manually and just creating a journal entry to adjust their inventory each year. I can no longer do that as the inventory account is a linked account and I can't use it in general journal transactions. 

Now my issue is, because all of their inventory items are at a 0$ value, the adjustments module will not let me post missing items.  I get a message saying "that amount will leave the inventory value below zero", and will not let me post. 

I cannot go adjust the invoices that were entered as $0.00 either, as it would increase the amount already in the inventory asset account. (ex - the inventory account is already at $15000 and i need to decrease by $2000 to $13000. If i go back and enter the value of inventory items it would increase the asset account $15000+ with each item I enter - when it is supposed to be at the $15000 and decreased by 2000 - if that makes any sense at all) - on second thought, I think I may not even be able to adjust those invoices?

I am ripping my hair out trying to figure this out - please help someone!