Once you log into CUC 12.5 GUI, click on Users on the left hand side, once there you should see the section where you search for the users based on whatever criteria but right above that, you should see a line of text that reads "Limit search to" wit...
Easiest way to do it, under where you search the users, change "Limit your search to" from All to Partition. From there just select the option "Display Primary and Alternate Extensions in Selected Partition" and search to your hearts content.
Hope it...