As I said, you can use either available FM object, e.g. fund source, and store monthly budget there. I.e. you will have fund source '01', '02, ... '12'.
As for two levels of control, you will have to create two ledgers: one will check the budget on fund source level (with commitment item and fund centre, of course) and assign to it tolerance profiles with warings only. Other AVC ledger will check the budget on FC/CI level only and tolerance profiles assigned to it will be with 'error' message.