With the quaint phenomenon of the castrati left behind in the 18th century, it was inevitable that the Jackson Five and the seven Osmonds would eventually wane (or else Wayne Newtonize themselves for the Vegas constituency). But that fell loss need no longer cast a cloud over the nation's junior highs. There is now a silver—or rather, Sylver—lining. That's the name of the upcoming first family of weenie rock. Consider the numbers. There are nine Sylvers—five brothers and four sisters. They have a No. 1 single, Boogie Fever. But perhaps the best numerical indicator of the Sylvers' arrival in the big time is 44—that is the total of back tax returns that they have finally been able to settle.

The Sylvers shrewdly made their move when they observed the voices of Donny Osmond, 18, and Michael Jackson, 17, cracking into lower register. Instantly, they regrouped their act around Foster, now 14 and a Michael look-and-sound-alike. Foster has already cut a solo hit of his own, Misdemeanor, playing Teeny Orlando to sisters Pat and Angie's Dawn, and it is his falsetto behind the group's latest 45, Cotton Candy. "When you get white kids comin' up to you for your autograph," Foster remarks, "you know you've made it."

Shirley Sylver, a 46-year-old divorcée trained in opera and piano, is the stage mother who made it all happen. She had given up her home in Apaloosis, La., as well as her musical ambitions, to marry a Memphis printer, moved the kids to South Bend, Ind., and finally to L.A.'s Watts. "There is no way I could have had a career and raised this family," she says. So she passed on her heritage one child at a time. "Every time I had a baby," she laughs, "I had laryngitis on the delivery table." To be sure, the Sylvers can all play at least one instrument by ear, and brother Leon has written about half the songs in their three LPs. The oldest kids formed an R & B act called the Little Angels that played at Harlem's Apollo Theatre and traveled with Ray Charles from the late '50s to the early '60s, at which time they broke up along with their parents' marriage. In 1971 the five youngest joined the original foursome, but it wasn't, Shirley says, until "Michael Jackson's voice had changed" that her kids began to score.

Mom runs their chartered Greyhound road show. The new business head disentangling their finances is Al Ross, a crack sports attorney whose clients include million-dollar basketball star Elvin Hayes. But Ross is not into it just for his percentage—he serves as tutor for the school-age members of the troupe during the six months of the year they are traveling.

The dormitory that the Sylvers call home (Leon and Charmaine are off and married) is a five-bedroom beach house in the L.A. suburb of Palos Verdes Estates. A housekeeper has been hired, but Mom still does most of the cooking. (The chow line recently grew by one when Olympia-Ann, though single, had a baby daughter.) Showbiz success or no, everyone has chores—"the boys, too," notes Olympia. "There's no chauvinism around here." There are also surprisingly few sibling uprisings. Their record producer, Freddie Perren, whose credits include Frankie Valli and Martha and the Vandellas, marvels that the Sylvers' "togetherness is incredible."

The garage has been converted into a rehearsal studio with mirrored walls for practicing the intricate routines diagramed by the man who previously choreographed the Supremes. Foster complains that the road schedule keeps him away from school and his eighth-grade girlfriend. To fill the time, he collects pennies. "Pennies aren't going to be made anymore," observes Foster, a savvy and most unprodigal son. The rest of the family loot not sluiced away to the IRS goes straight into savings for the children.

Of course, Shirley's biggest investment against the future may be the breathing lessons she's ordered for Foster. "You have to be very careful when the voice is changing," she explains. But once Foster's pipes reach the dreaded age of puberty, she'll still have one more son, Joseph, now 9, to keep those high notes coming.