If I am understanding what you are asking then the below should help.
1. Click on "Manage Nodes"
2. Change "Group By" filter to "Location" or whichever method you want to group your nodes.
3. Select the location/filter you want to work with and click the check boxes you wish to work with.
4. Once all of the nodes you want to work with are selected you should be able to click the more actions in the top and choose rediscover.
Let me know if you have any questions or if this wasn't what you were asking.