More than 60,000 women stayed in maternity homes run by the Salvation Army.
The organisation has now pledged to assist any inquiry into historic adoption practices, something the Government is considering.
Lieutenant Colonel Sheryl Jarvis, the Sallies' head of personnel, told the Herald the organisation was ready to co-operate.
"We would welcome any inquiry that would bring people healing. And we are open to meeting with anyone who wishes to talk with us about their experience as a Bethany resident."
An unknown number of young New Zealanders had their newborns adopted out to married couples during the so-called "baby scoop" era, from the 1950s to 70s.
The Australian Government formally apologised in 2013 for its estimated 250,000 forced adoptions, after an inquiry concluded many young women were deceived and threatened into giving up their babies.
Last month Pope Francis issued a sweeping apology while in Ireland for the past actions of the Catholic Church, and assured mothers it wasn't a sin to look for children they lost after going into homes for unwed mothers. They had been told for decades that it was.
In New Zealand, the previous National Government declined to order an inquiry after a petition by Maggie Wilkinson, who lost her daughter to adoption after giving birth aged 20 at St Mary's home for unwed mothers.
Jacinda Ardern presented the petition, and as Prime Minister in May said she was considering a select committee inquiry. However, there's been no update since.
The first of six Salvation Army Bethany maternity homes around the country opened in 1897, and the last closed in 2011. The homes were for both private patients and unwed mothers. Many babies born to the latter group were adopted.
At the Auckland home alone, there were 6364 women over a 10-year period. It isn't known what proportion were unmarried, or how many adoptions took place.
The Herald has spoken to a former resident of the Wellington home who said she told staff she wanted to keep her baby, but said it was made clear adoption would be best for everyone, and was what her family wanted.
"There were girls there from Australia. You could hear the girls - and I was one of them - crying at night."
She said it took an age for staff and a lawyer to get her to sign the paperwork. She had no idea the DPB was available and felt entirely without options.
Losing her child left her suicidal, and the trauma has had an ongoing effect on her life, she said. An inquiry would document part of the country's history.
"These children of ours - and grandchildren, great grandchildren - will know what happened to them."
Jarvis said the Sallies' focus was on the mother deciding on adoption, with family support.
"In no way were our staff supposed to influence those decisions in any way. The Salvation Army aimed to care for mothers during that time, regardless of the culture of the day."
Salvation Army Bethany maternity homes