I am not convinced that any of it has to be reported. Refunds of amounts deducted on a 1040 -- usually these are state income tax refunds, but they can be refunds of other taxes, or other expenses like medical -- are not income. They are adjustments to amounts previously deducted. Just because there is a line on the 1040 for reporting them, doesn't make them income. They are an asset of the estate, and maybe the estate is liable to amend the 1040 to reduce the deduction to the amount actually owed.
Does anyone know of an IRS or court ruling that addresses this question?