A second show on Tuesday was added for fan club members. But Osmond, who is overseeing the entire project, resisted moving into the arena because of the logistics of filming the reunion for a PBS special. The shows will be filmed for broadcast in March, followed by DVD and CD releases.

Sticking to the 827-seat theater "keeps the integrity of what we're doing," Osmond says. "We started on television, and this way it will play for a long time," he says of PBS's two-year window for repeating the special. "Anybody who wants to see it can see it and be a part of it that way."

The theater was designed for TV production, which will facilitate the high-definition shoot. "I originally wanted to do it in a TV studio," Osmond says. "It's not about the money, it's about doing what we came to do, which is capture this moment in time."

Doing the special for PBS means "it will be celebrated longer than if you were to do a normal network-type thing," he says. "Nowadays, unless you're 'Hannah Montana,' it's hard to make some of the networks understand the history. I think PBS really gets it and they jumped on quickly."

The concerts will be the first since the late 1980s to reunite the first four singing brothers -- Alan, Wayne, Merrill and Jay -- with Donny and Marie Osmond, who became breakout stars with their own solo hits and a TV series in the mid-1970s. Jimmy joined the original group in the wake of Donny's solo success and also recorded on his own. He now tours with Wayne, Merrill and Jay while Donny and Marie perform separately. "These are the only dates the entire year that we could all come together," he says.

The anniversary is timed to the special's air date, celebrating the original quartet's debut on a talent show. Alan, the oldest brother at 58, battles multiple sclerosis and his participation in the reunion concerts will be limited.

Monday events include an afternoon meet-and-greet for fan club members and a post-show party.

"We've had a good ride and I hope we have a few more good years," Osmond says.