When Marlo Thomas accompanied her husband Phil Donahue to Moscow last year, she had more in mind than sightseeing in Red Square.

The trip gave her the idea for what will be the first Soviet-American co-production of an entertainment show, her special "Free To Be . . . A Family," airing Wednesday (7 p.m., Ch. 4)."It's an entertainment exchange between kids and superstar performers from this country and the Soviet Union," Thomas said. "We present our favorite performers and they present theirs. It's a fun show of comedy and song, but the show also challenges destructive stereotypes about families.

"Our goal is to show children that every family, no matter who's in it or where they live, is a real family as long as its members nurture and love each other.

"We also talk about the global family. It's no longer `we' and `they,' we have to start thinking of `us.' Steve Martin talks about feeding the entire world with one turkey and how big it was would have to be. Carly Simon sings the song that became our theme, `Turn of the Tide.' It says we are the turn of the tide and we have to speak up."

The one-hour special is a sequel to "Free To Be . . . You and Me," which won Peabody and Emmy awards in 1974.

Thomas made arrangements for the special while her husband was taping a week's worth of his syndicated talk show "Donahue" in the Soviet Union.

"Free To Be . . . A Family" was put together later by means of a satellite hookup between the Hard Rock Cafe in New York and Gosteleradio Studios in Moscow.

Thomas is host of the special in New York and Tatiana Vedeneyeva is host in Moscow. Among the American performers are rock group Bon Jovi, actress Whoopi Goldberg, comic magicians Penn and Teller, singer-songwriter Carly Simon, comedians Lily Tomlin and Robin Williams, and Muppets Kermit the Frog and Miss Piggy.

"We started work on the special last September," said Thomas. "It was very complicated to put together. This is the first jointly produced American-Soviet entertainment program. . . . We have 40 Soviet kids and 40 American kids, and we sing over the `space bridge' satellite. The kids were selected a year ago and got to know each other by exchanging letters and photos."

A "Free To Be . . . A Family" book was published in 1987, and half a million copies have been sold. An album featuring many of the stars on the special was issued last month.

"Soviet rock star Vladimir Prezhnikof is on the show. I was surprised to learn the Russians dance to the same dance steps we do and know more about us than we know about them. They know all of our rock stars and see our movies."

Thomas said the first project, "Free To Be . . . You and Me" was an attempt to rewrite children's literature to eliminate sexual and ethnic stereotypes.

"There were too many stories about Prince Charming coming along and carrying the girl off," she said. "I wanted to liberate the definition of boy and girl the way we had liberated the definition of men and women. The new book liberates the definition of the family and expands its meaning."

With the special completed, Thomas is now on to other things. She's just completed a comedy-mystery called "In the Spirit." It co-stars Elaine May, Peter Falk and Olympia Dukakis.

"Elaine plays a Hollywood wife, and I'm a New Age health food store owner who thinks all the world's problems would be solved if people would just stop eating meat," she said. "We're being chased by someone who thinks we know about a murder."

Next, she will star in a feature film for Twentieth Century-Fox called "A Point of Light." It's a story of a rural family and probably will be filmed in Vermont.

She will also co-star with her father, Danny Thomas, in a CBS drama called "Deception." She said, "We play father and daughter," he said. "We look alike so what else could we play?"