Earlier this month, Ms Shortall had asked the commission be recalled to hear evidence from three witnesses.
For now, the new evidence is on the secure commission website and remains confidential, but it is all from former Pike River Coal Ltd technical staff member Udo Renk and middle managers Terry Moynihan and Greg Borichevsky.
The new evidence came to light three months after the commission closed its public hearings in Greymouth.
Ms Shortall wanted to be able to cross-examine the men, test the weight of the evidence, and ensure there was as much evidence before the commission as possible.
"Let them tell their story,'' she said.
It would ensure the commission's findings were robust, she said.
Families' spokesman Bernie Monk said if the commission had to reconvene, "so be it''.
"What has to be done, has to be done, for the sake of finding out the truth.''