BOSTON -- The prospective owners of the Boston Celtics have bolstered their bid by adding a local real estate development firm before Tuesday's meeting with an NBA ownership committee.

The Abbey Group will have an equal share with the original three partners, group chairman and longtime Celtics fan Robert Epstein said Thursday.

On Sept. 27, team owner Paul Gaston said he was selling the team to Boston venture capitalists Stephen Pagliuca and Wycliffe Grousbeck and Grousbeck's father, H. Irving Grousbeck, founder of Continental Cablevision and now a Stanford Business School professor.

The reported price of $360 million would be the most paid for an NBA franchise. The current high is $280 million for the sale of the Dallas Mavericks in 2000.

At the original announcement, the group said it was seeking more investors.

The prospective new owners will meet with the NBA ownership committee on Tuesday in New York.

"It could be a few weeks or more than that'' before an NBA decision is made, said Wyc Grousbeck, who expects to name more investors next week, "but I don't want to comment for anybody because that's not our role.''

On Monday, the NBA expansion committee meets in New York to interview two groups of prospective owners for a Charlotte, N.C., franchise. One of those groups includes former Celtics star Larry Bird.

The Abbey Group principals involved in the deal include Epstein, David Epstein and John Svenson. The Epsteins are brothers. Svenson is their brother-in-law.

They explored purchasing the Celtics before Grousbeck's group became involved. Robert Epstein said his group reached agreement with Grousbeck's group about three weeks ago.

"I'm extraordinarily pleased,'' he said Thursday. "When I was a youngster, I actually went to Bob Cousy's basketball camp and the highlight of my adolescence was when Bob Cousy complimented me on my game. I have no doubt he would not any longer.''

"It's a very natural group,'' Wyc Grousbeck said. "Bob Epstein's wife knew my mom 25 years ago in a crafts circle. (They) actually did weaving together in the 1970s.''

David Epstein said all the prospective managing partners are fans who would attend games regularly.

"It's just so awesome to be able to be a part of the ownership and the management of the Boston Celtics, the tradition and history,'' Svenson said.

The sale can be closed in a relatively short time after NBA approval, Pagliuca said, and the timetable has been "exactly what we expected.''

Gaston has been frugal to avoid the league's luxury tax, and an ownership change could signal a loosening of the purse strings. The Celtics had just 11 players to practice for much of the season because of an injury to Kedrick Brown.

Still, the Celtics' 14-7 record after Wednesday night's loss to Phoenix was the NBA's seventh best. And they're coming off their best season in 14 years, reaching the Eastern Conference finals where they lost to New Jersey.

Forbes Magazine recently estimated the value of the franchise at $218 million, 13th in the NBA, and well behind the first-place Los Angeles Lakers at $403 million.