To add custom Groupings to a CaseWare File you need to add it in the 'Groupings' section.
To navigate to this go to Engagement > Groupings and add a new grouping as shown below.
Once created, check the properties of the leadsheets you would like the grouping to appear in.
In the example below the Balance Sheet by - leadsheet properties are checked by right clicking within the leadsheet and clicking properties.
In this instance the structure dictates what accounts will be pulled into the leadsheet. Therefore the structure needs to be updated.
To navigate to this go to Engagement > Structures and add the new grouping to the structure as shown below (Click within the calculation box and then the 3 dots).
If you choose to create custom groupings and add them to structures, read the guidance around how to handle these when you update your file's groupings and structures as part of CaseWare annual updates in the staff update guide!