It seems you have to look at your brokerage statement , Schedule B to capture the lots that were sold and the proceeds of the merger transaction.
TT should have the basis that was tracked year by year from the K-1 Partner's Capital Account. There is a Schedule in the K-1 that summarizes the sale, sale date, Initial Basis, Cumulative Adjustments to Basis, Cost Basis (the net of the previous two), Gain subject to recapture, AMT and where on the Federal Filing (Form, Line and Column)
Caveat, I'm no tax accountant and went through something similar last year with Energy Transfer Partners, LP. The issue of suspended losses was difficult to treat on TT.
