I assume you launch UFT with the WPF addin loaded. Also, make sure you either open a GUI test, or create a new one.

1. In UFT, click on the Tools menu
2. Select Object Identification... from the drop down
3. From the Object Identification Window, click the Environment drop down and select Windows Presentation Foundation
4. Select the class of the object on the left by clicking it once
5. Over on the right-hand side, you will see the Mandatory Properties section. Click the Add/Remove button to add the property or properties you want to make mandatory by checking the box next to them.
6. When finished, click the OK button to close the Object Identification window.

*Note: This will only apply to new objects that are added after the change is made above. If you have objects in the OR, you may need to delete them and add them again manually, or record the script. You could edit the existing objects manually in the OR by adding properties to the object.