SO WHAT IF THEY HAVE NOT EVEN STARTED FIRST GRADE? ASHLEY Fuller and Mary-Kate Olsen, 6, the doll-face twins who share the role of Michelle Tanner on ABC's hit sitcom Full House, which begins its sixth season next month, already have this Hollywood thing figured out. "One time the executive producer promised to have a cake scene for them, and then he forgot," the girls' acting coach, Adria Later, jokingly recalls. "On the day of the taping, I walked in and announced, 'Ashley and Mary-Kate won't be in this week because there is no cake scene.' He immediately wrote a new scene."

Talk about having their cake and eating it too! The twins' income from the series, plus their royalties from the popular, talking Michelle doll (in trust until they are 18), is already more than enough to put them through college. From here on in, Ashley and Mary-Kate arc working on the proverbial icing. While they were in Vancouver, B.C., last spring making To Grandmother's House We Go, an ABC Christmas movie in which they will be seen side by side, their lawyer was busy in Los Angeles negotiating a big-bucks record deal. On July 9 the girls went into the studio to record an album of children's tunes (tentatively titled Brother for Sale). "I like the song called "I Want to Trade My Brother,' " says Mary-Kate. "Yeah," Ashley agrees with a giggle. "When we were rehearsing it, our brother Trent said, 'I hale that song!' "

Usually Ashley and Mary-Kate get along fine with Trent, 8, who assumes the part of Daddy when the three play house at the family's five-bedroom Cape Cod home in California's San Fernando Valley. (Baby Elizabeth, 3, sporting a makeshift leash, is relegated to the role of family pet.) Indeed, surveying the raucous household headed by dad Dave, 40, a mortgage banker, and mom Jarnie, 38, a former dancer with the Los Angeles Ballet, it's hard to believe that the Olsen twins are not only stars but have the third-highest popularity, or Q scores, on TV. "They showed me their room once, and they brought out all their toys and then started jumping on their beds just like normal kids," says actress Candace Cameron (Kirk's sister), who plays D.J., their oldest sister. "I think the only way fame would hurt them is if they continue to act as they get older and they don't really enjoy it."

With three years to go on their Full House contract, Mary-Kate and Ashley, who were just 9 months when they landed the role, have learned to be professional during their 16-hour weeks on the set. Too young to read their scripts—they go to school two days a week and have on-set tutors the other days—they act by mimicking the lines their coach speaks for them. "They've never said no to me," Later says. "They're always willing to try."

And when one doesn't succeed, the other steps in. "Mary-Kate is more serious, so she gets the serious lines to do," says Jarnie. "When they need someone to be more active or emotional, they let Ashley do it." Surprisingly, the twins are not identical but fraternal. Ashley is three minutes older and has the freckle under her nose.

"I like being an actress," says Ashley, mulling over her career options during a rehearsal break. "You want to be an actress until you are an old, old lady?" asks Mary-Kate. "I don't. I want to be a candymaker or cowgirl." Ashley considers that possibility and agrees, sort of: "I would like to be a candymaker and an actress too. The food scenes are so much fun, don't you think?"

ART DURBANO
VICKI SHEFF-CAHAN in Los Angeles

  • Contributors:
  • Vicki Sheff-Cahan.