The important feature is that the mortgage secures frequent and routine future advances to be added to the loan balance. What one must keep in mind when completing the Affidavit is that (a) the principal amount of the loan set forth in the Affidavit must always equal the principal.A future advance is a clause in a mortgage that provides for additional availability of funds under the loan contract without requiring another loan. A loan modification serves as an efficient way to alter specific loan terms, while leaving other original loan terms intact and enforceable. Modification of trust mortgages given in prior re-organizations. Mortgage or deed of trust recorded in another state.