WHEN I GROW UP, I WANT TO BE...
Now that she makes $12.5 million a film, DEMI MOORE can afford to hire someone younger to play herself. In Now and Then, a low-budget female-bonding movie she's co-producing, Moore, MELANIE GRIFFITH, RITA WILSON and ROSIE O'DONNELL play second fiddle to the girls who portray them as 12-year-olds. And although GABY HOFFMANN (Sleepless in Seattle), THORA BIRCH (Clear and Present Danger), ASHLEIGH ASTON MOORE and CHRISTINA RICCI (Casper) are young, they know the biz. "I didn't try to act 12," says Ricci, 15. "When people try to act younger, they come off looking...