How to Correct Errorrs in Form 1065 Balance Sheet

The balance sheet filed with my 2020 From 1065  was the first tax return for a newly formed LLC.  Unfortunately, the balance sheet did not reflect pending trades that had not settled as of the end of the year.  As a result, the balance sheet did not include acquired positions that had not yet settled and included stock for unsettled sales.  Since the balance sheet is inconsistent with the tax treatment, it will throw everything out of balance for the next year.

 

Do I need to go back and amend the prior year?  Is the amendment press difficult?