My father owned stock in just his name but before he passed away in 1991, he had my mother's name added to his stock as jt tenants with rights of survivorship. I have a copy of the certificate showing it reissued in both their names and it is dated May 1, 1990. Now my mother is in an assisted living home and part of the stock was sold this past year to provide funds for her. My question is... I have no cost basis for this stock which was bought at various dates from1980 through1982. It was originally Southern Natural Resources but has since changed hands... SONAT, EL PASO, and now Kinder Morgan. It was sold before the last merger so was El Paso stock at time of sale. I have searched for historical data to determine cost basis for Southern Natural Resources but can't find any back that far. Also since my mother's name was not on the stock until 1990, is that when she acquired the stock or is the acquistion date when my father bought it in just his name? Help would be appreciated!