> For the complete documentation index, see [llms.txt](https://docs.mashmatrix.com/mashmatrix-sheet/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mashmatrix.com/mashmatrix-sheet/functions_advanced/union_sheet/create_union_sheet.md).

# Create Union Sheet

You can create a union sheet both when creating a new book and when adding a sheet to an existing book.

To add a union sheet to an existing book, follow the procedure below.

1. Click the "+ (Create New Sheet)" button on the right side of the sheet tabs, and select "Add Sheet".
2. The "Create New Sheet" dialog is displayed. Select the "Union" tab.
3. From the list on the left side of "Union Sources", select the object you want to unite, and click the "Add Object" button.
   * If you cannot find the object you are looking for, you can narrow down the list by entering a keyword in the search box.
4. Repeat step 3 and add two or three objects to "Selected Objects".
   * To cancel an added object, select it in "Selected Objects" and click the "Remove Object" button.
5. Click the "Create" button displayed at the bottom right of the dialog.

<figure><img src="https://2214743720-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FOYt1c4qdNlLlHO5tcs5o%2Fuploads%2FDekKc7RDN54sHoGXD1Gb%2FCleanShot%202026-08-26%20at%2008.37.18%402x.png?alt=media&amp;token=316ec644-1541-4a65-a824-203f14cf829c" alt=""><figcaption></figcaption></figure>

When creating a new book, you can create one in the same way from the "Union" tab displayed in the "Create New Book" dialog. For creating a new book, see "[Create a New Book](/mashmatrix-sheet/functions_about_books_sheets/create_a_new_book.md)".

## Order of Selecting Objects <a href="#order-of-selected-objects" id="order-of-selected-objects"></a>

The order in which you add objects to "Selected Objects" has the following meanings.

* It becomes the order of the options of the "Object Type" column.
* It determines the order used when sorting by the "Object Type" column.
* The first object becomes the default object of a newly added row.

## Columns of the Sheet Just After Creation <a href="#initial-columns" id="initial-columns"></a>

When you create a union sheet, the sheet is displayed with the following columns placed in advance.

* The "Object Type" column
* A union column that unites the fields representing the name of each object
* Columns of the standard fields of the object selected first

You can add the columns you need after creation. For details, see "[Add and Configure Columns](/mashmatrix-sheet/functions_advanced/union_sheet/add_and_configure_columns.md)".

{% hint style="info" %}
You can select two or three objects for a single union sheet. The same object cannot be selected more than once. As with an ordinary sheet, the objects that can be selected for union are Salesforce objects.
{% endhint %}