If you have a SSAS tabular cube with a large number of measures in a particular measure group, you may want to group specific measures into display sub-folders.  Display sub-folders help keep a cube more organized and reduce the amount of scrolling end-users need to do to locate the measures they want to add to a pivot table in Excel.  As far as I am aware, there is no option to create a sub-folder from the SQL Server Data Tools GUI (without installing a 3rd party tool such as BIDS Helper).  Fortunately, you can create display sub-folders without the need to install a 3rd party tool by following the steps listed below.  Thanks to OpenSourceSQL.com  for the original blog post on this topic.

1. Right click the Model.bim file for your solution and choose View Code.  You’ll be presented with the XML behind the model.
2. Find the section related to the measure you want to add to a sub folder.  The actual tag where the measure is named is .
3. The XML tag that adds a sub folder is ….  Add this inside the tag and enter the desired folder name.
4. When you connect to the cube in Excel and add a pivot table, the measure should now be displayed in the appropriate sub folder.