The well-heeled homeowners of San Francisco’s Presidio Terrace neighborhood are assembling quite the army to help them win back the private street they lost to a South Bay couple when they fell behind — way behind — on their property taxes.

To lay plans for a showdown at the Board of Supervisors that’s still more than two months away, the Presidio Terrace Homeowners Association has hired a former assistant city attorney, Scott Emblidge, to run their legal operation. Another veteran of the city attorney’s office, former spokesman Matt Dorsey, is teaming with a onetime chief of staff for ex-Supervisor Bevan Dufty, Boe Hayward, to work the politicians behind the scenes and push the homeowners’ story to the media. Both are now with Lighthouse Public Affairs.

They all have their work cut out for them in trying to persuade the board to rescind the 2015 tax auction that resulted in Michael Cheng and Tina Lam of San Jose picking up the street near the Presidio for $90,100.

“Unless they can show clearly and convincingly that proper procedures were not followed, I see no reason to rescind the sale,” said Supervisor Aaron Peskin, who was recently visited by the homeowners’ team of advocates.

“Sales like this happen every day to all kinds of people and businesses,” he said.

It certainly does when they fall 30 years behind on their property taxes. That’s what the owners of 35 multimillion-dollar Presidio Terrace homes managed to do when it came to paying the $14 annual bill on their small, gated private street, sidewalks and other common areas.

When the total in back taxes, penalties and interest hit $994, the city put the property on the online auction block, unbeknownst to the homeowners association. Cheng and Lam outbid several other parties.

The first the homeowners knew they had lost their street was when an intermediary for the buyers contacted them about a possible sell-back. Far from admiring the entrepreneurial spirit of the immigrant couple, the homeowners charged that they were being shaken down by a pair of out-of-town speculators and went to war.

Their main target is the city treasurer/tax collector’s office, which they say sent the property tax bills for 30 years to an accountant who retired in the 1980s, then failed to tell them about the tax auction. Treasurer José Cisneros’ office counters that the bills went to the address that the homeowners association provided and that the city did nothing wrong.

The homeowners have sued to block the San Jose couple from reselling the property and are asking the supervisors to rescind the street sale — something the city has never done before. The couple would get their $90,100 back.

“There was a comedy of errors, and the homeowners take the responsibility that was theirs,” Dorsey said. However, he said, the city created “careless circumstances” that unjustly deprived the homeowners of their property.

Bottom line: The “careless notification process by the treasurer/tax collector’s office fell far short of the legal standard for a reasonable effort,” Dorsey said.

The homeowners scored a victory Tuesday when Supervisor Mark Farrell, whose district includes Presidio Terrace, persuaded his board colleagues to hold a hearing on the tax sale.

Farrell urged the supervisors to “get to the bottom of what happened” and said, “I want to make sure we have all the facts.”

Seated at the back of the board chambers were Cheng and Lam, the street’s new owners.

Cheng said he wasn’t worried. “I didn’t hear the supervisors say anything specific about rescinding the sale,” he said. “I feel sure that we are on sound legal footing.”

The supervisors’ hearing was initially set for Oct. 31 but was rescheduled for Nov. 28 to avoid a long hearing on Halloween.

So there’s time for everyone to make their case. But Peskin said, “My advice would be for the association to sit down with the new owners and work something out.”

San Francisco Chronicle columnists Phillip Matier and Andrew Ross appear Sundays, Mondays and Wednesdays. Matier can be seen on the KPIX-TV morning and evening news. He can also be heard on KCBS radio Monday through Friday at 7:50 a.m. and 5:50 p.m. Got a tip? Call (415) 777-8815, or email matierandross@sfchronicle.com. Twitter: @matierandross