A generation ago, Milton and Shirley Gralla's parents left this part of the world for America, where they could practice their religion in peace.Things turned out well for the Grallas, and two weeks ago the couple flew in from New York to begin making returns on their good luck. At an airy complex north of Moscow, the American publisher snipped the ribbon on the Milton and Shirley Gralla School for Jewish Children.By his side that morning was Hillel Zaltzman, who left his native Moscow for Israel in 1971. As executive director of the Jewish cultural society KhAMA, Zaltzman helped channel Gralla's money into a school where 100 children are being introduced to their religion. All of them are part of a growing investment coming in from abroad to enrich the lives of the 250,000 Jews in Moscow. Last year alone, $28 million was donated from Israel and America, for the twin purposes of encouraging emigration to Israel and building a culture here. Much of the money will go toward education, supplementing a Jewish network that now includes two other kindergartens, four elementary schools, three high schools, four rabbinical colleges and five seminaries, says Rabbi Pinchas Goldschmidt, who came to Moscow from Israel five years ago.As the Grallas accepted gifts at the school's opening, they smiled at the children who, they hope, will become the foundations of a new Jewish community. His gift, Milton Gralla explained, was less charity than a reunion with lost family."The parents of myself and my wife were from Russia and Eastern Europe," he said, as Zaltzman translated for the children and their parents. "A lesson they taught us is that we are the brothers and sisters of all Jews."The children I see here are as important to myself and my wife as my own grandchildren," he added. "I am so happy to be a part of this."Zaltzman stressed that the donations aim to improve Jewish families' life in their native country, not encourage them to leave it. The Moscow government is contributing generously to the maintenance of the new school, he pointed out -- the first joint project between the city and a Jewish group, and a good omen for future efforts.KhAMA, which has 100 workers in Russia, and offices in Israel and New York, operated in secrecy for 20 years, teaching Hebrew to 1,500 children without ever taking them into a synagogue. They worked with a constant fear of suppression. "The KGB was following us and we were following the KGB," Zaltzman remembered, smiling. But now, Russian Jews can and should practice their religion in the open, he said. Some incidents cast doubt on that goal, though. As last October's violence flared up, KhAMA administrator Greta Yelinson had just received agreement from the Supreme Soviet to establish the school. At 8 A.M. on Oct. 3, her telephone rang. She did not recognize the caller's voice."'So Greta,' he said," she remembered. "'You will be one of the first 10 we hang at Red October Square.'""I didn't leave home for three days," she added. But nothing could keep Yelinson away from the project, which has been her chief activity for almost two years. She is visibly proud of the school that has resulted. In many cases, the 100 schoolchildren now know more about their faith than their parents do -- they go home and instruct their families on how to observe the sabbath and high holidays."The prophets always said someday the children would be teaching their parents," Zaltzman said.