Four songs into their scorching, free set Thursday in the parking lot of Waterloo Records, Austin rock/soul band Black Joe Lewis and the Honeybears called up a quintet of African American men in bright blue suits and yellow shirts. Lewis had just sung his current single, "Booty City," but the tone would turn spiritual. Within five minutes, the guest singers, a Dallas-based gospel group called the Relatives , had the packed parking lot jumping in jubilation.

The Relatives are one of the stories of South by Southwest, a group that broke up in 1980 and didn't play together for 29 years until an Austin couple tracked them down and put out their debut LP in 2009. Most of the material was recorded 35 years ago.

The revived band has been tearing up audiences and is starting to build a following, thanks mainly to their championing by Lewis and the Honeybears, who include the Relatives on "You Been Lying" from their new album "Scandalous."

There aren't too many bands at SXSW that would call up another group they know is going to fire up the crowd, but Lewis said the tradition of soul bands trying to outdo each other doesn't apply here. "We want to take our music to a special place, and the Relatives are showing us the way," he said.

The Rev. Gean West said the recent turn of events — including being booked for a gospel show at New York's Lincoln Center in July — "is all part of a divine call."

"If that lady didn't buy our record at a garage sale and give it to her son, none of this would have happened," said West, who presides over the tiny, 25-member congregation of God's Annointed Community Church in West Dallas. "I don't think it's a coincidence."

The scratched 45 RPM record Antone's Records co-owner Mike Buck 's mom found for him about 12 years ago was "Don't Let Me Fall."

The Relatives had pressed only about 200 copies of that single and two others they released in the early '70s.

Buck played the gospel/soul record for another record collector, Austin graphic designer Noel Waggener , who was floored. "It was so unlike anything I'd ever heard before," said Waggener, who has worked as a soul DJ. "It was soulful and funky, but there were all these psychedelic touches."

In late 2008, Waggener and his wife, Charisse Kelly , started a vinyl and MP3-only label called Heavy Light Records and went in search of that strangely moving band they heard on the 45.

Waggener and Kelly had spent several months trying to track down anyone connected with the Relatives when they finally got a lead. During a Google search, West's name came up in a post by a preacher whom he had helped get started. It mentioned that West was on the Dallas Interfaith Council, and the couple were able to finally get West on the phone.

"Noel was talking about the Relatives, and I just couldn't follow what he was saying," said West, 76. "Finally I went, 'Oh, you mean my old group the Relatives?' I hadn't thought about the band in a long, long time."

Not knowing how much recorded material was available, the couple originally wanted to put "Don't Let Me Fall" on a compilation. Then they met Dallas engineer Phil York , who still had masters from a 1974 recording session that had never been released. With the three released singles, which Waggener was able to remaster from clean copies lent by DJ Shadow (Josh Davis), among others, Heavy Light put together a complete album — the band's first.

A record release party was set for October 2009 at the Continental Club. It would be the first time the Relatives, with four original members, including West's brother Tommie, would play in almost 30 years.

"It was a magical night," said Clara Reed, who worked as a bartender at the comeback show. "When they walked on stage, the audience didn't know what to think. But then they started

playing, and the whole place went nuts."

On the three-hour drive to Dallas the next day, the members talked about putting the band back

on the road. "It was the acceptance of that audience that made up our minds," West said.

Lewis and the Honeybears were on the road and missed that Continental Club show, but guitarist Zach Ernst got the LP, and the band became fans on first listen.

The Honeybears have exposed the Relatives to a younger audience, even getting them booked into the Austin City Limits Music Festival in 2010. At that show, in front of about 5,000 delirious fans, several members of the Relatives were seen wiping away tears.

"I think both bands have had an influence on each other musically," Waggener said. "Playing so many shows with Black Joe has made the Relatives rock harder. And Joe and the band have

been falling into that more spiritual groove."

Lewis sees the connection going even deeper. "Rev. Gean is just so positive," said Lewis, 29, from Round Rock. "He's our mentor, not just musically, but in every way."

When the Relatives practically stole the show at Waterloo Records, nobody was smiling more than Lewis and the Honeybears. And nobody jumped higher.

"They may not have made it back in their day, but to us, they're legends," Lewis said of the Relatives, who will also back them tonight at Lost Highway Records' 10th anniversary showcase at ACL Live. Saturday at 5 p.m., Black Joe Lewis and the Relatives play a free show in the parking lot of Jo's Coffee on South Congress Avenue. Prepare to move and be moved.

mcorcoran@statesman.com; 445-3652

Update: The date for the free show at Jo's featuring Black Joe Lewis and the Relatives has been corrected. It will happen Saturday.