Anna Osborne's husband Milton and Sonya Rockhouse's son Ben were two of the 29 men who lost their lives when explosions blasted through the coal mine in November 2010.
In December last year, all charges against Mr Whittall arising from the disaster were dropped.
The Ministry of Business, Innovation and Employment (MBIE) cited the lack of witness availability as a key reason for abandoning the prosecution.
More than $3.4 million in insurance money, which was earmarked for his defence, was paid out to the families of the dead men.
Ms Osborne and Ms Rockhouse have applied for a judicial review at the High Court into the decision to drop the charges, Radio New Zealand reported.
Ms Osborne said the money was "blood money" and she wanted justice.
"Sonya Rockhouse and I, we got together actually and thought there's got to be something more that we can do," she told RNZ.
"A lawyer got in touch with us and was happy to help us try and piece this together a bit and try to get some closure as far as justice to the families."
Council of Trade Unions president Helen Kelly also became involved, Ms Osborne said.
"Together we've all come up with what we believe is a hard case, but I'm sure we can win this."
The compensation had hurt nobody except the insurance company and had not brought justice to the families, she said.
"I want all the charges that...MBIE had charged Peter Whittall with, I want them to be reviewed."
She did not understand how the ministry had enough evidence to charge Whittall and then drop them all.
"The Pike families are the ones living a life sentence - we're paying for the crimes that we never committed and the people who are guilty are out there walking free."
She and Ms Rockhouse were prepared to fight for as long as it took to get justice, Ms Osborne said.
