Depending on the type of document, create an addendum at the end of the document or appendix by inserting a page break, centering the cursor, and typing "Addendum" and a title underneath that describes the purpose of the addition. Align the cursor to the left margin, indent the paragraph, and write the body of the addendum or insert the table or graph needed. Save the document.
For legal documents, ensure that the addendum is formatted according to the legal precedent. For example, when attaching an addendum to a will, some states require that there are two witnesses who both provide a signature after the addendum is complete. Only a person legally eligible to draw up the legal document is able to write an addendum. Consider consulting an attorney who specializes in the type of document written to approve or edit any addenda.
If the addendum makes a change to the original document, specify the section of the document and the exact change made. Add a date to the addendum to ensure the reader knows it is the most up-to-date version of the document, if necessary. Avoid drafting multiple addenda to one document. The more the document changes, the more confusing it becomes. Draft a new document if the changes made are numerous.