First of all, you should have been filing Partnership tax returns (Form 1065) all along. ALL income, expenses & depreciation is entered on the Form 1065. Then a K-1 for each partner is be generated for reporting of said info on their personal tax returns.
Please see a local professional to straighten all this out before you sell the property.
https://www.irs.gov/businesses/small-businesses-self-employed/partnerships
