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.