"Mr Mandela made it clear to (daughters) Makaziwe and Zenani that he did not want them involved in his affairs," trustee Bally Chuene said in an affidavit seen by the Star newspaper.
"The only persons he wanted involved were myself, advocate Bizos...And his other various nominees."
Chuene is one of the administrators appointed by Mandela to manage his investment funds, Harmonieux Investment Holdings and Magnifique Investment Holdings said to be worth over USD 1.7 million.
Last month Zenani and Makaziwe filed papers to have Chuene, rights lawyer George Bizos and Tokyo Sexwale who is a cabinet minister, removed from the boards.
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The two daughters claim that the three men were never appointed as shareholders or directors of the companies established in 2004 to channel the proceeds of the revered icon's artworks.
The exclusive artworks feature a framed imprint of Mandela's hand.
Chuene also revealed that Mandela wanted both Makaziwe and Zenani to be removed as trustees of the companies, after they were appointed by his ex-lawyer, Ismail Ayob without his consent.
Bizos, who is Mandela's long-time friend, has said that he will oppose the legal challenge, saying the ailing icon had explicitly asked them to help manage that portion of his estate.
The 94-year-old statesman is recovering at his Johannesburg home after suffering a series of health scares in the last six months.
A court date for the hearing has not yet been set.