In 1979 she got a job as the administrative assistant to Mr. Feinberg, who was then Senator Edward M. Kennedy’s chief of staff. The next year she followed Mr. Feinberg when he left to found the Washington office of Kaye Scholer, a major law firm. She accompanied him again, in 1992, when he went off to found his own law office, specializing in arbitration and mediation.

The first claims project Ms. Biros worked on was the Sept. 11 compensation fund.

The projects break down into two broad categories: those that the firm is paid to devise — for instance, with the Catholic Church clergy-abuse cases — and those done pro bono. Those have included such matters as the Pulse nightclub shooting, which involved the distribution of charitable donations.

“Whatever the issue is,” Ms. Biros said, “Ken and I brainstorm and come up with what we think is an appropriate protocol.” Those plans must be approved by the paying client, but after that the client has no authority over how the program is administered.

The research can be complex. In the system set up in 2014 to compensate victims of defective General Motors ignition switches, which led to 124 deaths and 275 injuries, the process started by researching what juries were awarding in similar cases, Ms. Biros said. Based on those findings, they decided the starting point would be $1 million for a death, plus $300,000 for a spouse and each child. Then, on top of that, economic modelers would compute a projected economic loss — in other words, estimating what the deceased would have earned if not for the catastrophe.

In cases in which people suffered life-altering injuries like brain damage or paralysis, the victims’ lawyer and she would each hire a “life-care planner” to compute the costs of a lifetime of home care, transportation, home renovations for access, and so on. “We’d go through line by line,” she said.

Robert Hilliard of Corpus Christi, Tex., a lawyer who represented ignition-switch victims both in court and before the Feinberg-administered fund, said his clients’ awards ranged from about $10,000 to close to $40 million. Some awards were greater than he could have gotten in court, he said, while some were smaller, although he added, “not that much less.”