Are you trying to think of a situation where you might need a change in a real estate transaction? Many contracts already contain a clause that defines how to make changes – it is likely that “this agreement can only be modified, supplemented or modified by the mutual written agreement of all parties”. Even if it doesn`t say you should make changes in writing, you should still do it – this will help avoid problems later. While an amendment modifies the actual contractual conditions, an addendum maintains all the original contractual conditions and adds new ones. . . .