Michigan Compiled Laws, Chapter 560. Subdivision Control Act of 1967 § 560.206

Sec. 206.  (1) The surveyor making the plat shall reconcile any discrepancies that may be revealed, so that the plat as certified to the governing body shall be in conformity with the records of the register of deeds as nearly as is practicable.

(2) When boundary lines between adjacent parcels, as evidenced on the ground, are mutually agreed to in writing by the proprietors of record or in possession, such lines may be the true boundaries for all purposes thereafter, even though they vary from the metes and bounds descriptions previously of record.  The written agreements shall be recorded in the office of the register of deeds.

(3) When reconciliation has been completed, the temporary monuments shall be replaced with permanent monuments meeting the specifications and provisions of this act for monuments.