Urgent!

I am currently on an interim audit of an auto mobile dealership company, where they give free gifts to the customers ( Neck rest in car for eg.) But no entry was passes all these years and now while conducting stock audit of the accessories division , i have came across various difference between the actual stock and the data shown by TALLY ERP9 . My problem is what should i do ? Can i pass back dated entries in 2016 ? But it would affect the opening and closing balances. Please help!