Dweezil and Ahmet, who were once so close that they recorded two albums together and made regular appearances on late-night TV, now seem to communicate primarily through lawyers, with disputes over trademarks and music licensing.

In addition to changing the name of his tribute project, Dweezil Zappa said that he would not carry any of the trust’s official merchandise or use any images of his father — whose likeness is also controlled by the trust — in promoting the tour. He will, however, play the same songs from his father’s catalog that he always has.

In an interview, Ahmet Zappa said he was not feuding with his brother but rather maintaining the integrity of the estate and preserving Zappa Plays Zappa as a family enterprise, available to any of the four children.

“I am not standing in the way of Dweezil playing the music,” Ahmet said. “He would just have to be in accordance with the family trust.”

Dweezil Zappa said that changing the name of his tour would “emancipate” him from dealing with the family trust. His complaints in some ways resemble those of a disgruntled artist warring with a record company: lack of communication, inexplicable delays, disagreements over payments from merchandise sales. The dispute also spills over into the division of estate property, like a set of guitars that Dweezil said were given to him by his father but, he says, were “repossessed” by his mother.

But the most contentious part of the dispute is over the minutiae of music licensing, an area in which the Zappa estate has long taken controversial stances. The family trust argues that for a show consisting largely of Frank Zappa’s music, performers cannot rely on the standard performing-rights licenses that music venues typically get from agencies like Ascap or BMI, but instead need special permission from the estate for “grand rights,” a term that usually applies to theatrical presentations.