An addendum can clearly spell out what is allowed and any special requirements to return the home to found condition upon move out. A lease addendum is a separate legal document that allows a landlord to add additional information or make changes to a lease agreement.Document Agreement: Draft a written addendum or new lease agreement outlining the terms and obligations for a monthtomonth lease. In general, things to include in a lease addendum might be: Your name. The rental property address. In an addendum to a lease, you will need to add the dates, names and addresses of all parties involved in the original lease agreement. A lease extension addendum is a legal document extending a lease between a landlord and a tenant. When compiling the legal paperwork to add a tenant to a lease, you can create an addendum to the existing lease or create a new lease agreement. Use the Change in Lease Terms Addendum to Residential Lease (Form CLT) to make changes to the terms of a residential lease. 1. Contact the Landlord.