You can add new rows in a Sheet List to create placeholder sheets. You can leave these placeholder sheets as-is to represent consultant sheets, or you can convert them into project sheets using the New Sheet dialog.
To add placeholder sheets to a sheet list

On the Modify Schedule/Quantities tab, you can add or delete sheets, or filter unused placeholder sheets.
Rows panel
Insert drop-down
(Data Row). This adds a new row representing a placeholder sheet to the Sheet List, but note that the placeholder is not associated with the Project Browser. On the ribbon, click
(New Sheet).
The new external sheets are created and display in the Project Browser.
