There were two distinct groups of stars at the Capital Centre yesterday afternoon -- the familiar, magazine-cover faces who were rehearsing the Inaugural Gala, and the unglamorous families who were getting all the attention.

The Washington-area families who upstaged the stars were relatives of the American hostages in Iran -- special guests invited to the rehearsal by Frank Sinatra, who produced the event.

As Ethel Merman belted out "Everything's Coming Up Roses" from the stage and Sinatra orchestrated a madhouse of scrambling technicians, a succession of celebrities scheduled to perform at the gala filed through the section reserved for the families, shaking hands and signing autographs -- Donnie and Marie Osmond, Ben Vereen, Rich Little and Mel Tillis.

"I just thought, 'Why not come see Frank Sinatra?'" said Penne Laingen, wife of U.S. charge d'affaires Bruce Laingen, the highest-ranking of the hostages. "Of course, it helps take your mind off everything."

"I came, but I brought my Bellboy," said Lisa Moeller, as she opened her coat to reveal an electronic beeper clipped to her belt. "I'm ready in case anything happens," the wife of Staff Sgt. Michael D. Moeller said.

Organizers of the gala said Sinatra's invitation to families of the hostages to watch the rehearsal was extended last week, before events made release of the hostages seem imminent. Eighteen hostage families, more than a third of the total, live in and around Washington -- more than in any other area in the country.

In addition to Laingen and Moeller, also attending the rehearsal were Pat Lee, wife of hostage Gary E. Lee; Margaret German, wife of Bruce W. German; and Susie Roeder, wife of Lt. Col. David M. Roeder. Some of the wives brought along their children, and a few of the youngsters clutched autograph books as they arrived at the arena.

Most family members declined to talk to reporters. Those who consented to be interviewed expressed an optimism tempered only slightly by the snags in getting the hostages home that cropped up throughout the afternoon.

"I'm more nervous at the moment than excited," said Laingen. "I just want them to get on the plane."

Laingen said she does not plan to go to West Germany to meet her husband, explaining that she believes the hostages will need "time to decompress for a while, to get any physical problems out of the way."

Laingen has said previously that she believes any agreement to get the hostages out of Iran would have to preserve the honor of the United States. "We've not lost any honor at all," she said yesterday of the terms of the settlement. "All we're doing is getting back to the status quo ante. We're simply returning to them what was theirs originally."

Moeller said she was "a little concerned" at yesterday's delays, but said she is "sure they are coming home."

"They're coming home, because if they don't, Iran doesn't get its money," she said. "All they want is their money."

Moeller said she would go to Germany if her husband asked, but that it would be his decision. She predicted some adjustment difficulties for her family when her husband gets back home, but added, "We've made it through the last 14 1/2 months. Being together as a family again won't be one of the top-10 tough things to do."

Earlier yesterday, Pat Lee, who attended the rehearsal with her 11-year-old daughter Dana, said she was "somewhat worried by my lack of excitement about all this, but perhaps it's because I'm so tired. I keep having this vague niggling feeling that something could fall through.

"I told Dana not to get too excited until we see Daddy get off the plane in Wiesbaden," Lee said in a telephone interview."But she has never let herself get overly excited. . . I think in this case waiting is easier for children.

"One thing Gary will probably want to do is come home and go into his little house and look out at the woods and think, this is my kitchen, this is my house and I can go anywhere I want without being blindfolded," said Lee, who has received only 12 lines of correspondence from her husband since July.

Bonnie Graves, wife of embassy public affairs officer John Graves, spent yesterday in her Reston home trying to stay calm. Like Lee, Graves has concentrated on easing her husband's readjustment.

"For the first month I expect there will be mostly family reunions. After that John may turn to some of his writing projects, but there may be times when he just wants to shut the door and that's why I made the little retreat for him," said Graves, who has turned her son's bedroom into a study for her husband, complete with cherished family pictures and piles of news magazines.

Helping hostages catch up on the events of the last 14 months appeared to be a preoccupation of many relatives. Becky Cooke, the 19-year-old sister of Donald Cooke, 25, said her brother probably has found captivity particularly difficult because he could not keep in touch with world news.

"He loves politics and current events and knowing what's going on," she said in an interview from her Towson, Md., home. "Like Mount St. Helens blowing up . . . everyone in America knows that happened and the hostages don't."

Other families said they were trying to control their emotions until they know the hostages were on their way home.

"We plan to celebrate in stages," said Susie Roeder of Fairfax, wife of Lt. Col. David M Roeder. "The first will be when they're in air space, when the wheels are up and locked. . . The next celebration will be when they're in Germany and we talk on the telephone."

James F. Babcock, brother-in-law of Laingen, agreed that it was important for the families to maintain a grip on their emotions even though the crisis appears to be in its waning hours.

"Everybody's feeling good," said Babcock yesterday, "but we know this last mile is perhaps the hardest."