An enterprising investor on BiggerPockets discovered this useful nugget in the Fannie Mae Servicing Guide from 2017: Section D1-4.1, Information Relating to Transfers of Ownership Applicable to All Mortgage Loans D1-4.1-01, Determining Whether a Transfer of Ownership Is Permitted (11/12/2014) […] D1-4.1-02, Allowable Exemptions Due to the Type of Transfer Unless the previous borrower requests […]