First of all, if he is getting SSDI, that is state disability, the amount is not great, but the state will eyeball any payee closely, and it is important to keep a good ledger of expenses paid.
If it is Social Security ( SS) they have their expectations of a payee also.
You will be basically budgeting for the person, in a timely manner.
You may run into problems with the person if they have unrealistic expectations of how much money they can spend, or hwo they can spend their money.
I worked for Mental Health agencies where payees and recipients were taught how to manage the money, and were supervised when necessary.
Just be sure you know the difference between the state and the Fed. expectations, and SSDI versus SSA.
Be aware that if, for some reason, the recipient is no longer eligible for the monthly check, SSA checks are considered for the previous month.
So say someone becomes inelgible for the monthly check in the 3rd week of the month.
SSA will want ALL of that check back.
Better check with SSI about that, too.