For some of its most valued friends - group tickets buyers - the Kennedy Center yesterday morning tossed a novel party at which Big Times Names sang for their luncheons at their own expense.

There was Martha Scott, whose first movie in 15 years, "The Turning Point, is an enormous hit, here in her role as co-producer of Plumstead Playhouse to introduce authors Jerome Lawrence and Robert E. Lee in a scene from their Eisenhower-bound play "First Monday in October."

In a white suit, director-choreographer-costume designer Geoffrey Holder explained how "Kismet," had become the National-bound musical "Timbucktu." After Bruce Hubbard had sung "This Is My Beloved" - and to resounding applause - Holder glided into a dance from the show.

Though a non-performer, the Center's Martin Feinstein, talking about its coming ballet attractions, confided a piece of news: During Ballet Theater's spring season, dancer-choreographer Mikhail Baryshnikov's newest ballet, from "Don Quixote," will have its world premiere.

(Feinstein, who with Roger L. Stevens, the Center Chairman, takes off today for Tokyo, had put off the trip until after the party.)

Stephen Simon, whose second Handel Festival will be held Jan. 8, Feb. 12, and April 2 in the Concert Hall, sat at a piano to explain that the "Messiah" Hallelujah Chorus wasn't the only music Handel wrote. He presented arresting portions of "Poro," which will have its first performance in the United States next month.

Charles Bright, director of sales, had a properly melodic finale. Composer Jerry Bresler and lyricist Lyn Duddy, introduced by star Gene Barry, presented three songs from "Turn on the spotlight," the story of a film star and his children due next month at the National "Spotlight" has the sound and beat of a musical show hit.

You couldn't call it a hard sell, though the creators and performers weren't bashful about putting their best fronts forward. During the luncheon which followed not a few orders came in for theater parties from representatives of Wilmington, Richmond, Baltimore, Hagerstown, Frederick and points west. One even wanted all 1,104 Eisenhower seats for a performace of "First Monday in October," so well had playwrights Lawrence and Lee assumed the roles they've written for Larry Gates and Henry Fonda as Supreme Court justices.

Which was the point of the party. Now the agents and group leaders will go back to their organizations, presumably enthused over what they viewed and start forming groups and theter partes, many at reduced rates so that the organizations can make some money from benefits.

The custom is regularly followed in New York, but this was a first for Washington. At a time when theaters no longer can get by on 60 per cent capacity, group sales can turn red ink to black.