The Pike River families are supporting a move to show footage of an intact body following the mining disaster.
Filmmaker Tony Sutorius is hoping to add the video, filmed four months after the last explosion, in his upcoming Helen Kelly documentary.
Families spokesman Bernie Monk says it has to be done, to show people the bodies of the 29 men killed in the mine could indeed be recoverable.
"The core group are really sorry that this had to go to this extreme to prove to the people - the powers that be that have been trying to stop us," he told Newshub.
"The families are really hot now on pursuing what they're pursuing, and they won't stop."
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Union leader Ms Kelly helped in the families pursuit for justice over the 2010 disaster.
"Helen Kelly stood beside us," said Mr Monk. "She just pointed us in the right direction and made the monumental movement where we are today."
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Pike River Minister Andrew Little says he is aware of the footage.
The documentary on Ms Kelly is due to be released in cinemas on Suffrage Day, September 19.