I explored the idea of EP having a financial motive early in the case. But when we found out that EP inherited from her mother and is reasonably wealthy now, that doesn't seem to be a strong motive.
However, "Patterson said in the statement that she was worried she would lose custody of their children". I realise that was in the context of her husband accusing her of poisoning his parents so she "dumped the hydrator in the tip and panicked".
Woman at centre of Victoria mushroom lunch that left three dead says she feels trapped in her home because reporters are camped outside
www.theguardian.com
"Erin’s in-laws and several church elders had reportedly gone to her home on the 29th to
discuss new arrangements for Simon to see the former couple’s children."
An alleged poisoning is captivating Australia, where authorities suspect Erin Patterson intentionally laced a lunch of mushrooms and beef Wellington for her former in-laws, killing three and sicken…
nypost.com
I have never been aware before that child custody was the reason for the three deceased and the survivor to attend the lunch. I had only read in the media that it was a "mediation".
We have not been given any information as to what the present child custody arrangements are. Maybe EP had argued her case and received full custody of the children previously (perhaps due to SP's illness). Perhaps since he recovered, he has been talking to his parents about gaining shared custody or even full custody of their children which has angered EP. So maybe her in-laws suggested meeting over a lunch and invited the Minister and his wife to mediate the discussions. Perhaps SP had already set up a court date to proceed with this so he didn't think there would be any value gained by his presence so he cancelled the lunch at the last minute.
What is the definition of an unstable parent?
Examples of unfit parents include those who have drug or alcohol problems and foster an unsafe living environment as a result or a parent with a mental illness who is unstable.
A mother can lose custody of a child if the Court determines that custody would not be in the child's best interest.
movementlegal.com.au
Only about 11% of fathers gain full custody of their children in Australia. Perhaps SP has evidence of EP's mental instability? Maybe the children would rather live with their father?
What age can a child choose to live with a parent in Australia?
The Family Law Act 1975 in Australia
doesn't provide a defined age when a child can single-handedly choose which parent they want to reside with.
Australian law does not have a set age for children to refuse parental visits. Discover what courts consider when making custody orders.
justicefamilylawyers.com.au
IMO if child custody was the reason for their mediation, if EP thought that SP's parents were going to argue against her having joint of full custody in court, and she thought there might be a chance of the child custody arrangements changing to her disadvantage by something that the in-laws had evidence of, could that be a strong motive for murder?