If you have a large hierarchy, you can use the Search toolbar field to search all levels of the hierarchy.
The search will look down at each branch of the tree and stop on the first member containing the search text. You can then navigate to the next matching member using the navigation buttons.
If many members are returned by the search text, it may be better to use the advanced search option, which will display all matching members.
Having built a members list you can save it using the Save button. This can then be loaded into other reports.