A City Hall panel Wednesday night recommended nearly all of the Sweeney family’s Treasure development rights be stripped from a program that would allow landowners to shift their rights to another property, a startling move that endangers what has been seen as the key piece of ground in play in the discussions.

The Park City Planning Commission, on a 4-2 vote, forwarded the program to the Park City Council with a positive recommendation. The panel, though, made several crucial changes to what had been under discussion in recent weeks. Adam Strachan and Mick Savage cast the dissenting votes. Savage was especially skeptical, wondering whether there is demand for development rights in places where they would be moved toward. He conceded, though, he does not oppose the overarching idea of shifting development rights.

The most significant of the changes concerned the rights to the Treasure development site, situated on a hillside overlooking Old Town and on the slopes of Park City Mountain Resort. The Planning Commission recommended that approximately 10 percent of the development rights attached to the Treasure land be allowed to be shifted. City Hall staffers had wanted 50 percent of the Treasure rights to be in play under a program.

The disparity could have wide-ranging implications on the overall discussions about Treasure. Representatives from the Sweeney family and a City Hall team have been negotiating in hopes of reaching a conservation deal involving either half or all of Treasure development rights, which date to an overall project approval granted the Sweeneys in the 1980s.

The program to shift the rights is seen as being critical to a conservation deal. But if the amount of the development rights that could be shifted from Treasure remains at the approximately 10 percent that was recommended on Wednesday night, a conservation deal could be far costlier since the other upward of 90 percent would remain intact.

Treasure is envisioned as a 1 million-square-foot project combining residential units, commercial space and a convention area. It would be situated off streets like Lowell Avenue and Empire Avenue. It has encountered widespread opposition from Parkites, and the Planning Commission has numerous concerns about the blueprints.

Mike Sweeney, one of the family’s representatives in the conservation negotiations, attended the meeting. He did not provide input, though.

The Planning Commission since December has had concerns about allowing the Treasure development rights to be shifted, with the hesitancy based on concerns about whether the square footage from Treasure would fit elsewhere in Park City rather than the panel wanting the project to remain intact at the hillside site.

The Planning Commission recommendation included three other locations in addition to Treasure where development rights could be shifted from, known as sending zones. The three are located in the upper reaches of Old Town, on or close to streets like Ridge Avenue and Daly Avenue. The three have been a peripheral part of the discussions, which have been focused on Treasure.

The panel recommendation also designated two places where development rights could be shifted toward, known as receiving zones. They are the Bonanza Park district, centered along streets like Bonanza Drive and Kearns Boulevard, and Snow Creek Plaza, wedged between Kearns Boulevard and Park Avenue. City Hall staffers had recommended just Bonanza Park be labeled a receiving zone.

Numerous points were covered by the Planning Commission during the Wednesday meeting. They included the value of the development rights that would be put into play, whether the Bonanza Park district is the proper spot for additional development and whether places like Prospector or the mountain resorts should be turned into receiving zones. Two people testified during a brief hearing.

The City Council is not bound by the Planning Commission recommendation. The elected officials are tentatively scheduled to begin their discussions about a program on either March 3 or March 10.