unsold shares in a cooperative

I work for a management company that did a horrible joba at keeping their books. The management company received 24 million to develop 2 apartment buildings then converted ownership to co-op selling 15000 shares. The money received from the sale was used to pay the construction loan and the balance is development fees. There are 5 units still unsold for the last 5 years. All shares are issued and outstanding by the Apartment corp and the developer pays the corp maintenance dues. My question is how do you record the shares on the books of the developer? I am really hoping their is an accountant that is familiar with this that can assist. Thanks.