That confirmation provided enough incentive for the museum to develop an exhibition on Paul and Hedvika Strnad, as well as their American relatives. The challenge was to transform Hedvika’s drawings into three-dimensional reality.

Image Kathie Bernstein, director of the Jewish Museum Milwaukee, has been involved in the project for more than 15 years. Credit... Tom Lynn for The New York Times

In the fall of 2012, the Milwaukee Repertory Theater had done a production of “The Diary of Anne Frank,” giving a special performance at the Jewish museum. The show had required period costumes. So a year later, as work commenced on the Strnad exhibition, Ms. Bernstein and her staff turned to the theater’s costume artists.

Jessica Hartman Jaeger at the repertory theater assigned a dozen people from the costume shop to the task. Over nearly 3,000 hours spread across 10 months, they matched the colors in the drawings; determined the likely fabrics, like rayon and bouclé; extrapolated the sketches into patterns; and assembled the dresses and coats with matching hats and shoes.

To Ms. Jaeger, these looked like clothes meant for fun, similar to what a young woman might have worn for a day of shopping or a movie matinee. Yet all the spunk and verve they exuded stood in contrast to what had befallen the Strnads. Unable to get out of Czechoslovakia because of the United States’ tight restrictions on immigrants and refugees, they were interned in the Theresienstadt concentration camp, deported to the Warsaw ghetto and killed without any record.

“I felt so inadequate,” Ms. Jaeger recalled. “You want to do justice to the designer. You want her vision to be realized. But you can’t talk to her about it. And the reason why is tragic.”

Even as the dresses were being made, another piece of history dropped into place. Ms. Gettinger had been searching for the niece who had filed the Yad Vashem form, Brigitte Neumann Rohaczek, and ultimately found her listed in a footnote to a German-language book about the Kindertransport, which had rescued Jewish children. She wrote to the author: No reply.

At about this point, in late 2013, a college student studying abroad in Germany, Tyler Grasee, contacted Ms. Gettinger asking for a summer internship. She put him to work trying to find Ms. Rohaczek. Within weeks, Mr. Grasee had her address and telephone number in Nuremberg.