Diana Ross did it with Lionel Richie. Glen Campbell did it with Tanya Tucker. And Barbra Streisand did it with Donna Summer and Barry Gibb. Each pair was brought together by musical matchmaker Charles Koppelman—Ross and Richie to record the No. 1 Endless Love, Campbell and Tucker to make the smash single Dream Lover, Streisand and Summer for their disco chartbuster No More Tears (Enough Is Enough), and Streisand and Gibb for the title cut on their 20 million-selling Guilty album. "Most people dream of romance while listening to music," says Koppelman, "but I think of other artists who could sing the same song better."

Koppelman, 42, whose seven-year-old Entertainment Company grossed $15 million in 1981, also acts as executive producer for such solo artists as Cher, Engelbert Humperdinck, Dolly Parton and Tom Jones and groups like the Four Tops and the Marshall Tucker Band. While record sales as a whole are taking a nose dive, Koppelman is busy successfully blending country music with pop, rhythm & blues with jazz, classical with contemporary. His company currently owns more than 10,000 songs that have earned 14 gold records (sales of 100,000 each), eight platinum (one million sold) and three double platinum (two million) records. "I worked with Charlie on the Guilty album," recalls Walter Yetnikoff, president of the CBS Record Group. "His creative instinct to marry the artists and producers and deliver them presents a powerful package to the industry."

Last September Koppelman and Streisand's longtime love, Jon Peters, decided the Richard Parker-Bobby Whiteside ballad Comin' In and Out of Your Life was right for Barbra's Memories album. Two months later, just in time for the Christmas record-buying rush, Koppelman made sure Streisand released Comin' In as a single. The cut created enough advance interest in the album to sell two million LPs in six weeks.

While Ross and Richie were recording Endless Love in the studio last year, Koppelman continuously interrupted from the control room to offer suggestions. "I didn't know who he was," recalls Ross, "but this little guy kept saying the right things." Several months later Charlie and Diana became better acquainted when he helped her find the lyrics for a disco tune she wrote with Ray Chew and Paul Jabara, Work That Body. "It sounded good and was exactly what I wanted," says Ross. Koppelman, acting as creative consultant, also encouraged Ross to release as a single her version of Frankie Lymon and the Teenagers' 1956 hit Why Do Fools Fall in Love as a new single for RCA. "If I believe in a concept and the timing is right," he boasts, "I can always sell it."

Koppelman's own career as a tune-smith was mercifully brief. "I wrote terrible songs," admits Charlie, who gave up trying shortly after his graduation from Long Island University with a degree in physical education. "So instead I went into the business side of music with a friend, Don Rubin." They produced records for '60s stars like Darin, the Turtles and the Lovin' Spoonful.

When they sold the company for $3 million to Commonwealth Records in 1968, both men were retained to run the music division. They split up three years later, after Charlie was hired by CBS Records to head its domestic publishing division. He rose to veep for worldwide distribution, a job he held until 1975, when one of New York's largest private landlords, Sam Lefrak, became smitten with Koppelman's musical moxie and backed him as a solo. With Lefrak he started the Entertainment Company. "If you want music, get Charlie," says Lefrak. "As for business, the only difference in renting an apartment and renting a song is that you don't have to paint the song every two years."

That business also requires that Koppelman live four months a year in a Beverly Hills Hotel bungalow (stereo-equipped, of course). But Charlie tries to spend time with his wife, Bunny, in the 70-year-old, music-filled colonial home on Long Island's North Shore which they share with their children: Brian, 16, Stacy, 13, and Jennifer, 12; adopted daughter Lynda, 25, lives in Manhattan.

Koppelman's plans include producing musicals for prime-time and cable TV, videodiscs, radio shows and, of course, more records. Whom will he pair up next? Charlie isn't saying, but the possibilities are as endless as the number of "tomorrows" in Tomorrow, another single he's bringing out this month from the young star of the film Annie, Aileen Quinn. How about Stevie Wonder and Loretta Lynn? Wayne Newton and Wendy O. Williams? Mick Jagger and the Mormon Tabernacle Choir? Stay tuned.