The sister-in-law of Dominic Perrottet has rejected the suggestion she had been put in an “impossible situation” and lied under oath to cover illegal donations to her husband, an inquiry has heard.

Anita Perrottet, wife of Charles Perrottet, told the New South Wales Independent Commission Against Corruption (Icac) on Wednesday that hundreds of thousands of dollars in payments to her were for “strategic and marketing advice”.

She said she provided verbal advice to Beckington, run by Christian Ellis and Jeremy Greenwood, and JPG Advisory, run by Greenwood. Perrottet could only recall one client from her work for Beckington, for which she was paid as much as $333,500, saying the advice she gave included “creating websites”.

The inquiry heard that for a single quarter in January 2022, she was paid almost $255,000 by JPG Advisory for verbal advice alone.

As part of its inquiry into corruption into people associated with the NSW Liberals, Icac is investigating whether between 2020 and 2023, Ellis, Greenwood and Charles Perrottet took prohibited political donations from fugitive property developer Jean Nassif and his company Toplace, including for outcomes sought by Nassif.

The men allegedly anticipated receiving $2m to be distributed evenly between them.

On the inquiry’s first day, counsel assisting, Dr Peggy Dwyer SC, said evidence would suggest that Anita Perrottet was a “conduit” for payments totalling $661,000, equalling her husband’s alleged share of the funds.

At one point on Wednesday afternoon, asking about 2023 changes made by Charles to an invoice he created in 2022, Dwyer said: “Mrs Perrottet, can I suggest to you, you have been put in an impossible situation because you are being asked to lie under oath to cover for your husband?”

“I reject that. I’m not lying,” said Anita Perrottet, who asked to swear an oath on the Bible at the start of her evidence. She said any invoices made or changed by her husband would have been at her instruction.

The commission heard that Anita Perrottet, who worked in communications in the financial sector and subsequently ran an alcohol delivery company, Deliver Me Drinks, became the sole director and shareholder of Macquarie Consulting when it was set up in August 2020.

Asked about a $10,000 a monthly retainer she was paid by Beckington, she said she worked 15 to 20 hours a week under a “flexible arrangement”, for which there was no written proposal.

She could only recall one client from her time at Beckington, Greyhound Racing NSW. Anita Perrottet, who said marketing was “my background, so I have a good understanding”, said Greenwood would brief her, and she may have read “media articles” about the industry, but had never been to a greyhound race at the time.

Dwyer asked, “Why on earth would [Greenwood] need you then for strategic and marketing advice if he was giving you all the information?”

“He would tell me the issues,” said Anita Perrottet. “And I would come back to him with advice on strategies or marketing opportunities for them.”

“I vaguely remember proposing creating websites and stuff specifically to educate people on how to properly humanely treat [dogs],” she said.

The commission heard on Wednesday afternoon that she was paid in three lump sums after the first 12 months, following an invoice of $150,000 sent by her husband, including a $30,000 finder’s fee. The payments added up to $170,500, being more than the amount invoiced.

Asked about a message from Charles Perrottet to Christian Ellis in July 2021 in which he wrote “just sent you back the updated invoices”, she said that Charles would have done so at her request. She said that she did not know anything about a significant amount of money paid to Beckington by Toplace on the same day.

Dwyer suggested that the “true situation” was that the invoices were being drawn up “just to make up a number that was coming in for your husband Charles”.

“No, that is incorrect,” she said.

Anita Perrottet said the clients she advised JPG Advisory on from the start of 2022 included Greyhound Racing NSW, the state’s Catholic Cemeteries board, and a vaping client whose name she could not remember. Under questioning from Dwyer, Anita Perrottet said her research on vaping may have included reading articles in a hard copy paper or on social media. The commission heard that her laptop had been seized in a search.

Dwyer said: “Mrs Perrottet, this is rubbish that you are making up because you don’t want the commission to have a way of checking whether or not you researched it on your computer,” she said.

“That is not true,” said Anita Perrottet. She said the advice she gave included “ways in which they could stop minors from vaping”, including “removing the flavours, looking at UK, US models”.

Dwyer later asked: “Did it occur to you that you were getting money for jam in this year?”

“No,” said Anita Perrottet. The commission heard that for the last three months of 2022, she was paid for two invoices to JPG of $90,333 and $153,333, totalling $254,666.

She said she had no knowledge of a payment of $150,000 from Jean Nassif to JPG advisory around that time. She said she was not aware of visits by Charles Perrottet with their two children to Nassif’s home, described in messages from Charles to Nassif in 2022.

The commission heard she could not remember if she had ever been a member of the Liberal party and she denied her husband’s role as the “muscle” or a “power broker” in the conservative Christian right faction, headed by Dominic Perrottet.

“I don’t agree that that was necessarily the case,” she said. “[Charles] was obviously involved in politics and obviously very supportive and happy for his brother.” She will give evidence to the commission again on Friday.

Charles Perrottet, who is based in Melbourne with Anita and their two children, has taken a leave of absence from his role as head of strategy and commercial development at BP in Australia and New Zealand during the inquiry, at which he will appear on Friday. He has previously denied any wrongdoing.

In a statement, BP said it “respects the independence and integrity of the Inquiry currently under way in New South Wales”.

Dominic Perrottet is not named as a person of interest in Icac’s allegations and no allegations whatsoever are made against him.

Icac’s inquiry continues.