Sergio Ortega is referenced, with his songs, in La canción en el sombrero, the volume of memoirs published, in his native Spanish, by Horacio Salinas, the musical director and lead guitarist for Inti-Illimani.
Since the "divorce", as they are calling the legal and highly acrimonious break-up of the group, Salinas fulfills the same functions
for the newer entity, Inti-Illimani Històrico.

While Ortega's anthemic song is most closely identified, it seems, with Quilapayún,
Ortega is essential to an entire generation of Chileños, be they listeners or professional musicians.
Salinas acknowledges "El Pueblo Unido Jamás Será Vencido", as he must, given that his book is more than anything an account of Inti-Illimani's history of writing, recording, and performing music, with only carefully prepared and discreet remarks about the band apart from the music.

Salinas does volunteer a few interesting things.
Sergio Ortega, when the shocking assassination of Allende and the hostile takeover of the Chilean government happened, was...where? Had he already left the country? If I read right, he was already in Europe.
Everyone knows, of Inti-Illimani, that they were attending an event in Italy when the worst happened, and that thus the band was exiled from their native Chile for the next sixteen years. (Although they did perform in South America, in other countries. And Jorge Coulon, anticipating their return, would find a place to live in Argentina.)

Jorge Coulon's brother, Marcelo Coulon, was not at this point a fulltime Inti-Illimani member, although back in Chile Marcelo had, years earlier, subbed for Jorge during one recording session.
When Pinochet rose to power in Chile, Marcelo himself was in Europe, although not with Inti Illimani.

Salinas has some first-hand reminiscences of Inti-Illimani working with Ortega in exile.
Ortega was an artist of strong and fixed opinions, and band members who disagreed with him would find themselves up against a confrontational composer.