@Lillian4 , I have lived experience of schizoaffective disorder.
Like @tyme says, when the illness takes over, my thinking can sometimes be out of my control. For me, this is because my judgement becomes impaired. It's not that my personality itself changes, but I do do things that are out of character. I might become more impulsive, including with my spending, or I might become paranoid and act based on that.
Schizoaffective disorder is two-pronged - there is the mood component and there is the psychotic component. Which one, or both, does your son suffer from the most at this present time?
My first two episodes were primarily psychotic, and my last two mood. Over time, I have gained considerable insight into these, (lucky for me,) but not everyone who is afflicted does.
I think, in terms of the spending, you could either do what @tyme suggested and let him live off his own income. Or, if this is too dramatic a step, you could allocate/budget/ration the money into different portions. One way to do this is to make different accounts for different spending purposes. Other budgeters like to go old school - they have a special binder folder and they work with physical cash. So one portion might be for groceries, another for health care, another for leisure, another for eating out...etc. This is called 'Cash Stuffing. Find what works for you and your son.
See this webpage for more info: https://www.investsmart.com.au/investment-news/cash-stuffing-how-this-budgeting-method-works/
