The mortgage modification agreement is a legal document between a lender and borrower to change an existing loan's terms. Regulatory Agreement, HCD Assignment, the HCD Modification and any other document evidencing, securing, guaranteeing or otherwise relating to the HCD Loan.The guarantors should be required to participate in any negotiations with the borrower relative to a potential modification agreement. XXVI. A loan modification agreement is a legal contract between a borrower and a lender where alterations are made due to the borrower's inability to repay that loan. The Modification Agreement defines the changes to the home loan.