Jonathan survived a Seconal overdose when he was 9. “Those were my husband’s pills,” Mrs. Cheney testified years later, offering little else in the way of explanation.

Jonathan and the youngest, James, had “a lifelong venomous relationship,” one court document claimed. The middle child, Jennifer, would, in time, steer clear. She lived in the apartment until she was 27 but then did not see her mother for 20 years, Mrs. Cheney once said. Diane, a later suit claimed, “on repeated occasions, psychologically and sexually abused her siblings while they were growing up.” There have never been details of those claims.

After Jonathan became Diane in the mid-1970s, she disappeared from the family and the apartment for years.

The Oldest Comes Home

Diane Wells came home to Central Park West in 1989, when she was 36, calling from somewhere she did not name and saying she was out of money, Mrs. Cheney would testify. The mother said her daughter could start a new life in Apartment 9B.

If she did, much of it seems to have been focused on the apartment itself. Mrs. Cheney had bought it when the building went co-op in the early 1980s. On the ragged Upper West Side of the time, apartments that now go for $4 million were selling for $150,000 or less.

After Ms. Wells moved back in, the mother and daughter, who did not work, each had her own locked room facing a short hallway that led to a book-lined foyer. In scrawled, undated notes, Ms. Wells described some of what preoccupied her hour after hour, chain smoking in the quiet apartment.

Their mother had given James and Jennifer, both single and in their 40s, hundreds of thousands of dollars to buy Manhattan apartments, Diane Wells wrote. “Fear of what will happen to me,” she wrote. “Worse because of no money to live, + see you getting old + it upsets and scares me.” From the mid-1990s on, numerous million-dollar insurance policies were purchased on Mrs. Cheney’s life, arranged for by Ms. Wells but paid for by Mrs. Cheney with premiums of $45,000 and up that strained even a trust-fund budget. They named Ms. Wells as the sole beneficiary. James Cheney said in court filings that Diane convinced their mother she would need the money to pay the apartment maintenance and other costs of staying there after Mrs. Cheney died.