The finances seem a tangled mess even after separating in 2015, not with just the mother's inheritance, but moving Simons name from one title to another and the interest free loans (but indexed to inflation) that she (or was it she and Simon) made to two of Simon's sibling families of around $400K each.
I remember there was also media report somewhere that the siblings were making the repayments to Simon, though they were supposed to be separated. Maybe these agreements went south and is a contributing factor of her anger against Simon and his family.
In wonder if the prosecution will delve into the financial situation, as depending what the financial situation is and particularly the loans, it could add another layer to demonstrate resentment against Simon and the family above what the court has seen so far from text and facebook messages.