Fannie Mae does not permit the appraiser to change the intended user statement. They do, however, permit the following clarification of Certification #23.
Permissible clarification of Certification #23
"The Intended User of this appraisal report is the Lender/Client. The Intended Use is to evaluate the property that is the subject of this appraisal for a mortgage finance transaction, subject to the stated Scope of Work, purpose of the appraisal, reporting requirements of this appraisal report form, and Definition of Market Value. No additional Intended Users are identified by the appraiser." (This is from an old FAQ which is no longer available.)