Jude Donnelly, who is Mr McLachlan's colleague, told the inquiry when she heard back after making contact with the Prime Minister’s Office, they informed her the visa had already been processed.
Mr McLachlan said he does not have a personal relationship with the Home Affairs Minister, but has met him about half a dozen times.
“It’s a normal relationship that I would have with a minister on either side of politics,” he said.
The AFL boss recalled receiving a call from his second cousin, Callum McLachlan, who told him that he had been trying to “get hold of a relevant office” for someone who “had previously worked for them and had become a friend of the family”.
Mr McLachlan said his cousin asked if he was able to help, and that he then contacted his government relationships officer, who is a former political staffer, Jude Donnelly.
He said he had not spoken directly with Mr Dutton about the issue.
AFP asked to investigate leaks
The Australian Federal Police has been asked to investigate the leaking of documents linked to claims the Home Affairs Minister misused his ministerial intervention powers to assist au pairs.
Secretary of the Department of Home Affairs Michael Pezzullo has told a Senate inquiry the matter had been referred to the AFP with his authorisation.
“Unauthorised and possibly criminal disclosure of official information is all things being equal always referred to the police,” he told the inquiry.
Peter Dutton personally intervened in tourist visa decisions just 14 times since taking on the immigration portfolio four years ago, the Senate inquiry heard earlier on Wednesday.
The Senate legal affairs committee is examining whether Mr Dutton misused his ministerial discretion to grant two European au pairs visas in 2015, despite the reservations of border authorities.
The first question put to senior bureaucrats at the public hearing in Canberra on Wednesday was from Labor senator Murray Watt: "Really there's only one question here today: what's the go with the au pairs?"
Home Affairs secretary Michael Pezzullo said Mr Dutton had used his ministerial discretionary powers to grant more than 4129 visas since assuming the role in December 2014.
The minister granted more than 2000 visas in 2015 alone.
"These powers build flexibility into an otherwise highly prescriptive visa process," Mr Pezzullo told the hearing.
However, the two young women in question came to Australia on tourist visas, and Mr Dutton has only intervened in such cases about 25 times since taking on the portfolio.
Under further questioning from Senator Watt, Mr Pezzullo acknowledged the number of tourist visa interventions could actually be as low as 14.
Mr Pezzullo also said it was possible the first time Mr Dutton had intervened in a tourist visa decision was in the case of the first au pair.
"That might well be the case, it's just a matter of checking the record," he said.
No compliance work was done by the department to see whether the au pairs were abiding by their visa conditions, but both of the young women left the country on time.
Mr Pezzullo refused to comment on leaked documents connected with one of the au pair cases, saying the security breach has been referred to federal police.
"I am not prepared to speak to documents that have been put into the media through unlawful and indeed criminal disclosures that have not otherwise gone through the protections that are provided by this parliament," he said.
Hours into the public hearing, Senator Watt grew frustrated with officials who were unable to say whether the turnaround times on the two au pair cases was faster than usual.
"I hope we've got someone here today who can answer some of these questions," the Labor senator said.
AFL boss Gillon McLachlan will give evidence via teleconference to explain his involvement in lobbying Mr Dutton to overturn the deportation of a French au pair.
Alexandra Deuwel was detained at Adelaide airport in October 2015 after admitting she intended to work in breach of her tourist visa for grazier Callum MacLachlan, the AFL boss' second cousin.
Mr MacLachlan contacted the AFL boss, who directed his government relations guru - former Liberal staffer Jude Donnelly - to forward an email from his cousin to the minister's chief-of-staff.
Mr Dutton is also facing questions about a second au pair he saved from deportation - an Italian woman who was planning to work for his former Queensland police colleague.
Mr Dutton has consistently denied any wrongdoing in both cases, saying he had no personal link to anyone involved.