1. Run OpenOffice Calc Join (Merge, Combine) Multiple Sheets & Files Into One Software.
2. Click the "Add Writer File(s)" button to add files. Then an open file dialog will appear, hold CTRL or SHIFT key to select multiple files. To add all files in a folder, click "Add All Writer Files in Folder" then select a folder.
3. To start joining the selected files/documents, click the "Join To One File" button.