LOS ANGELES — Inside a home recording studio known as the Utility Muffin Research Kitchen, where the late Frank Zappa composed and recorded some of his most adventurous works, his youngest son, Ahmet, reflects on his father’s legacy.

It is a rich musical heritage from one of rock ‘n’ roll’s most beloved figures, but one that has become entangled by a contentious family battle.

The Zappa Family Trust owns the rights to a massive trove of music and other creative output by the songwriter, filmmaker and producer – more than 60 albums were released during Zappa’s lifetime and 40 posthumously. Like the intellectual property of many rock stars, the Zappa archives controlled by the trust are potentially worth at least tens of millions of dollars, according to one music insider.

Since the October 2015 death of Zappa’s wife, Gail, however, their children have become embroiled in a feud over control of the trust, which is millions of dollars in debt, pitting one brother and sister against another brother and sister. At issue is not just a celebrated artistic legacy but even which of the children can perform using the Zappa name and profit from it.

“Now, we’re becoming ‘that family’ – the spoiled brats arguing in public about who deserves what,” wrote Ahmet in an open letter about the dispute on the website zappa.com.

On this day, sitting in the recording studio, beneath a portrait of his father, Ahmet, 42, is contemplative. “It’s emotional for my older sister and my older brother and certainly my little sister,” Ahmet says. Thanks to a decision by their mother, he and his younger sister, Diva, 36, share control of the trust – to the dismay and anger of their older siblings, Dweezil, 46, and Moon, 48, who got smaller portions of the trust.

It was “the most hideous shock of my life,” Moon says in a separate interview of the day she learned of her mother’s division of the trust. “It’s comical, the level of betrayal. That’s all I can say.”

As beneficiaries only, the two eldest siblings won’t see any money from the trust until it is profitable.

Dweezil, who achieved fame in the ’80s as an MTV personality and for the last decade has served as a musical ambassador by performing his dad’s music, received a cease-and-desist letter from the trust after he announced that he was being forced to perform his upcoming tour as Dweezil Zappa Plays Frank Zappa instead of using his longtime moniker, Zappa Plays Zappa.

In response to the trust’s action, Dweezil renamed his performance series 50 Years of Frank: Dweezil Zappa Plays Whatever the … He Wants – the Cease and Desist Tour.

“You’ve only been told that you can’t keep using the name without agreeing to a fee of $1 per year,” Ahmet insisted in his open letter.

Speaking on the phone from London after a trip to Stonehenge for summer solstice, Diva says that the last year has been difficult on so many levels and that she and Ahmet are doing the best they can with a difficult situation.

“We are grieving and are being forced to put aside our grieving so that we can take care of everybody in the family, for the good of all, and to maintain the legacy and everything that my mother and my father put in place to protect us and take care of us for our lifetime.”

FILMS BRING NEW INSIGHTS

This should be a prime moment for remembering Frank Zappa and introducing new generations to his music and ideas.

June marked the 50th anniversary of “Freak Out!” the dada-esque debut double album from Zappa and his band, the Mothers of Invention. A recent deal negotiated by Ahmet with Universal Music has set in motion an extensive reissue campaign enabling a regular flow of Zappa reissues and unreleased recordings. And a new documentary, “Eat That Question: Frank Zappa in His Own Words,” features televised interviews, appearances and performance footage from Frank’s life, including his work in the decade before his death as a free-speech advocate battling explicit music labeling.

“His legacy is full of misconceptions. That’s one of the reasons we did the film,” says “Eat That Question” director Thorsten Schutte.

Often glossed over, for example, is Frank’s contemporary orchestral music. “This is how media works,” says Schutte, whose film premiered at Sundance. “You take certain cliches and then you perpetuate them and then you get this hairy freak that smokes pot and eats baby chickens on stage, which is very far from reality.”

Another planned documentary, “Who the … Is Frank Zappa?” recently made news when it broke a fundraising record in its category on Kickstarter with pledges for more than $1.1 million. The movie won’t see release for a few years, but director Alex Winter has been given full access to the trust’s archives and promises a deep dive. In fact, some of the Kickstarter money is financing the digitization of the trust’s film and video archive.

One worker heading this initiative is Joe Travers, whose role for the last 20 years as the trust’s official Vaultmeister places him at the center of Frank’s oeuvre. A Zappa fanatic since he was a preteen, Travers is responsible for identifying and preparing many of the posthumous Zappa records that have been issued as well as overseeing the remastering of Frank’s studio albums.

The stock that drives that demand is housed in the Vault, the Zappa home’s multi-room, climate-controlled space crammed floor to ceiling with boxes of tape reels. The volume is overwhelming, the collected recordings of music and film from a man who from an early age was obsessed with not only music but the documentation of it.

TREASURES PACKED UP

Until recently, the home that Ahmet described as Gail’s “super groovy artistic space” also contained a few lifetimes’ worth of art, musical instruments, recording gear, artifacts and memorabilia. But now that the house has been put on the market, most of that has been loaded into trucks, some sent to the auction house Julien’s, the rest to a cold-storage facility.

For Dweezil, the contents of the Vault contain more than notes and melodies. He grew up surrounded only by what Frank was working on or listening to. “I didn’t hear the radio that I can even remember until I was about 11 or 12. I only ever heard Frank’s music, what he was working on at home or listening to at home.”

Dweezil recalls Frank listening to rhythm & blues records, classical music and Bulgarian folk music. “So I heard all of this music, and all of it had different arrangements and different instruments and different time signatures.”

After his 1993 death in the home’s master bedroom following a long battle with prostate cancer, Gail inherited the family’s holdings. That wasn’t surprising. Gail ran the business while he was alive and earned a reputation for her tough management style. After his death, though, Gail became a polarizing figure among Zappa followers. She was fiercely protective of Frank’s music and threatened to sue tribute acts she felt were diminishing his work. Gail was diagnosed with cancer in early 2014 and died a year and a half later in the same bedroom where her husband passed.

As trustee of the Zappa Family Trust, Ahmet is responsible for turning the tapes and other recordings in the Vault into money. Before she died, Gail gave him a crash-course in running the business. As she weakened, he assumed more responsibility. Eventually, says Ahmet, “we had a family meeting and my mother explained to the rest of the kids that I was taking over.”

Gail made the Ahmet assignment official in her will when she divided the kids’ share of the trust. Ahmet and Diva each received 30 percent and Moon and Dweezil got 20 percent each.

To say Moon and Dweezil were surprised by the imbalance is an understatement.

Moon, the eldest child, says she and Gail had a rocky relationship, but in her mother’s final year and a half after the cancer diagnosis, Moon tended to Gail’s needs, driving her to oncologist appointments and bringing her meals.

“I was showing up because that’s what you do,” she says. “I still loved her.”

For Moon, the most painful part was that as her mom’s health deteriorated, she thought she and Gail had fully made amends. In hindsight, Moon believes Gail was asking forgiveness with the knowledge that her eldest child would be devastated by the slight to come.

“It’s complicated enough to be grieving the loss of a mean mom,” Moon says, “and then to find out she was meaner than I could have possibly comprehended.”

“She’s a mean little sucker,” said Frank with a tone of admiration from beyond the grave in the documentary “Eat That Question” when asked about Gail. “She’s an excellent boss’ wife. Everybody knows that Gail is the boss’ wife.”

Ahmet doesn’t see Gail that way at all. “She demanded respect and got the respect, and that’s really unusual. She was the greatest,” he says before interjecting, “Well, it depends on who you ask. Anyone who has the opposite opinion must have done something.”

Asked later about the public argument, Ahmet says, “I think it’s embarrassing. I don’t like it and I feel it’s not accurate. But I want nothing but the best for my brother. The part that hurts my feelings is I have no reason to stand in the way of my brother’s success, my older sister’s success, my younger sister’s success as it relates to anything Zappa related.… I’m not doing anything other than having to do what’s in the trust.”

Neither Moon nor Dweezil agree with that interpretation. Citing a “prudent person clause” that gives Ahmet license to change the terms of the trust, Moon says, “I don’t care how many times Ahmet says it. He has a 100 percent ability to make any and all changes to the trust. So I have to laugh every time he says, ‘My hands are tied.’ ”

A MOTHER’S WISHES

At a rehearsal space in North Hollywood, in a room with a full stage and sound system, Dweezil and his band have just practiced a number of Frank songs that will land in the upcoming sets for the tour, including “Catholic Girls,” “Harry You’re a Beast” and “Keep It Greasy.” Dweezil’s a dynamic, dexterous guitarist and leads his band through Frank’s oft-gymnastic structures and time signatures with a confident sense of purpose.

Regardless of who holds the legal title, Moon says, Dweezil’s natural inheritance is a dedication to music. “He knows Frank in a way that none of us will ever know Frank, because he can play the music,” she says. “He can literally be in Frank’s fingers, touching those instruments.”

After the rehearsal, Dweezil expresses frustration with his brother. “He’s saying, ‘It’s this amazing one-dollar deal, bro.’ You’re not saying the part about how you’re taking 100 percent of the merch,” Dweezil says.

“I’m just moving along, doing what she requested,” says Ahmet of their mother’s wishes.

Diva remains steadfast in her commitment not only to Ahmet but to the entire family. “Our father is someone who meant so much to so many that we have an obligation to maintain his integrity and everything he stood for as best that we can,” she says.

Earlier in the week, Diva had traveled to Prague to attend “Musics by Frank Zappa: Orchestra En Regalia,” which featured the Czech National Symphony Orchestra premiering previously unheard works in collaboration with a team of expert Zappa players (including Vaultmeister Travers on drums).

Frank and Gail’s youngest child, holding back tears, describes an emotional performance. “There was so much love in the room. Both my parents were there, and it just felt like everybody was there. It was alive.”