A Border Force officer “formed the view” that the first woman, who came in June 2015, was planning to work and therefore revoked her tourist visa.
But the minister’s office intervened on “public interest” grounds to prevent the woman’s deportation.
She was granted a visitor visa and allowed to stay in Australia, but still without the right to work.
The AAP journalist who broke the story in March reported the woman made a phone call to a contact while she was in detention, and was then granted the new visa shortly afterwards.
Labor has pressed for answers on whether the contact was an associate of Mr Dutton, or otherwise connected to the Turnbull government.
The department confirmed the issue was raised through its liaison officer based in Mr Dutton’s office.
But the department would not be drawn on who the au pair called before the intervention took place.
“This is a matter for the individual, not the department,” Home Affairs wrote in its response.
The department’s answers do reveal the total cost of fighting the freedom of information request was more than $10,000. The case made it all the way to the Administrative Appeals Tribunal.
Some documents were eventually released, but details about the au pairs’ identities were redacted.
A lawyer for the department told the tribunal there was “no evidence whatsoever” that the au pairs had any personal relationship with Mr Dutton.
The department briefed Mr Dutton’s office on the matter on three separate occasions through March and April this year.
The minister responded angrily to the initial reports in March, accusing the journalist of “seeking to suggest” that his own family had employed the au pair, or benefitted in some way.
“In my capacity as minister, I have never acted outside the Ministerial Code of Conduct,” Mr Dutton said at the time.