Mich. Comp. Laws § 600.849

Sec. 849. When the validity of any order or sentence of the probate court is in question in any other action or proceeding, everything necessary to have been done or proved to render the order or decree valid, and which might have been proved by parol at the time of making the order or sentence, and was not required to be recorded, shall, after 20 years from such time, be presumed to have been done or proved, unless the contrary appears on the same record.