There is not yet a built-in task filter to do this, but it is on our list of improvements.
One way to filter by WBS now is the following:
- Note that this method requires that WBS summaries have task IDs.
- If your schedule was imported from P6, they may not. To create IDs, go to Options>Synchronisation>Primavera P6 and enable "Use WBS Code for Summary Tasks".
- To assign IDs in Synchro, select the WBS summaries with missing IDs and select Plan>Reassign IDs
- In the task list, right click in the header to Customise Columns
- Add the WBS Path column to the Selected Columns
- In the task list, right click in the WBS Path column header and choose Custom Filter
- Change the operation to Contains and enter the ID of the WBS summary for which you want to show all child tasks
- Optionally, Add another row to the filter and choose OR for the logic to filter by a second WBS path
- The operation Matches can be used in filters in conjunction with wildcards (* or ? to replace any string or a specific character respectively)