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Last year, for Juliana Koo’s 106th birthday party, the choreographer Jacques d’Amboise rehearsed her great-grandchildren in a number that they performed. “He scared them,” recalled Mrs. Koo’s daughter Genevieve Young.

Two things were different at Mrs. Koo’s birthday bash this year, held on Sunday night at the Pierre hotel, four days before she was to turn 107. Mr. d’Amboise, a family friend, watched from the sideline as Kay Gaynor, a choreographer from his National Dance Institute, taught the steps. And there was a new member of the once-a-year family dance troupe, the first of the fifth generation to join in: Olivia Slaughter, 3, a step-great-great-grandchild. She hopped and twirled in the tribute to Mrs. Koo, whose second husband, Dr. V. K. Wellington Koo, was a Nationalist Chinese diplomat and prime minister who also signed the charter that established the United Nations.

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The family has been giving parties for Mrs. Koo every year since 1995, when she turned 90. She gave a speech in 2005. “I never give speeches, but I decided that at least on my 100th birthday, I should try,” she began.

There was no speech this time, but as always, there was a family-and-friends photograph, which at a gathering like this was a sprawling portrait with more than 140 faces. Children, grandchildren, great-grandchildren (and Olivia) filled a staircase and crowded into the space in front.

Mrs. Koo took her place in the center. Around her were the three people who organized the party: her daughters Genevieve Young, who is known as Gene and was vice president and editorial director of Bantam Books, and Shirley Young, a former vice president of General Motors and a founding member and governor of the Committee of 100, a Chinese-American leadership group; and Oscar L. Tang, a financier and philanthropist and the widower of Mrs. Koo’s third daughter.

Gene Young said a wall in Mrs. Koo’s apartment in Manhattan was covered with group photographs from past parties. “There’s no room left,” she said. But she said a place for the latest would be found.

Mrs. Koo was born in Tianjin in the year Theodore Roosevelt began his second term and the Russo-Japanese War ended. Her first husband, also a Chinese diplomat, was posted to Manila at the beginning of World War II and was arrested and eventually executed by the Japanese. Mrs. Koo and her daughters survived. She worked at the United Nations and married Dr. Koo in 1959.

“Somebody asked her the secret of long life,” said Ying-Ying Yuan, a step-granddaughter of Mrs. Koo. “She said, ‘No exercise, eat as much butter as you like and never look backwards.’”

Shirley Young said her mother also likes pork bellies, “especially the hot part, but she doesn’t overdo anything.”

“And she doesn’t take any medicine,” she said. “When doctors give her medicine, she usually hides it, or when she takes something, she takes half a pill. People keep on giving her Chinese herbs, things like that. She never takes them.”

James Fox, a former general counsel at HarperCollins who has known Gene Young for more than 40 years, said that for Mrs. Koo’s 100th birthday in 2005, Gene Young invited some of her friends from Wellesley, class of 1952. “Her mother said: ‘Gene, I don’t want you to sit with those women. They’re too old for you.” Ms. Young will turn 82 on Tuesday.

On Sunday there was a bit of opera, a performance of “Un bel di vedremo” from Puccini’s “Madama Butterfly” by the soprano Ying Huang — Mrs. Koo’s favorite aria, Shirley Young said. Later Mrs. Koo was serenaded by G.E. Smith, the lead guitarist in the band Hall & Oates and the musical director of “Saturday Night Live” from 1985 to 1995. He said he played “old-time traditional Chinese music that I learned off of YouTube” on a mandolin. “Then I played ‘On Moonlight Bay.’”

A few minutes later, Mrs. Koo danced with her son-in-law as the band played “Moon River.” He had asked for a slow number, he said. “She said, ‘Faster, this one’s too slow.’”