Victoria’s highest court has been urged to dismiss Erin Patterson’s appeal against her triple murder conviction, hearing that the case against her during trial was “overwhelming”.

On Thursday, three judges of Victoria’s court of appeal continued hearing arguments regarding Patterson’s bid to have her conviction overturned.

While Patterson, 51, is appealing against her convictions, the Director of Public Prosecutions is also appealing against the sentence handed down to her, arguing it is “manifestly inadequate”.

In September, Patterson was sentenced to life imprisonment, with a non-parole period of 33 years, for the murders of her estranged husband’s parents Don and Gail Patterson and his aunt Heather Wilkinson.

She was also convicted of the attempted murder of Heather’s husband, Ian Wilkinson, who survived the lunch after spending weeks in hospital.

Crown prosecutor Jeremy McWilliams told the court on Thursday that all seven of Patterson’s grounds for appeal should fail.

“This was an overwhelming case and the court ought to conclude that convictions were inevitable based on the evidence,” he said.

The court heard on Wednesday that Patterson’s grounds of appeal included that the jury sequestering was irregular, that cell tower evidence and evidence of death cap mushroom sightings should not have been included at trial, that photos and videos related to foraged mushrooms should have been included, and that the cross-examination of Patterson and the prosecutor’s closing address were unfair.

Two related grounds of appeal were that evidence taken from Patterson’s conversations with Facebook friends had been used to imply there was a motive for the killings, despite the prosecution also telling the jury there was no motive.

But McWilliams completed the prosecution’s response to Patterson’s appeal on Thursday by saying many of the grounds lacked substance, and in some cases were not the subject of any concerns raised by Patterson’s lawyers at the time.

He said there was no evidence she had an “innocent” interest in foraging mushrooms, and that no other witness had given evidence she had this interest.

Of the criticism of Patterson’s cross-examination by Nanette Rogers SC, he said that it was conducted thoroughly and with a “duty of fairness”, and that trial judge Justice Christopher Beale had intervened when it appeared her lines of questioning had gone as far as possible.

He described ground six, which describes the miscarriage of justice which occurred because of Rogers’ closing address, as a “Frankenstein” of a ground, that “bundled up” a series of unrelated matters.

Ian Wilkinson, the only surviving lunch guest, was again in court on Thursday. Patterson watched on via a video link from Dame Phyllis Frost Centre, the state’s women’s prison.

The court will hear arguments on Thursday afternoon relating to the prosecution’s appeal on sentence. It is seeking for Patterson to be resentenced to life imprisonment without parole for her crimes.

The hearing continues.