Anyway you need to play with targets to configure the needed schema. About targets which cannot be edited, I can suggest the workaround:
- For example open "Deployment Plug-in for Windows (x86) - Install" policy
- Copy or remember the Target's name of this policy ('Computers without Deployment Plug-in installed on Windows (x86)')
- Click on Apply-to -> Computers
- In "Select Computers" window click on "Open" button
- Find the Target's name from p.2 and apply it.
Now you have editable target with the same structure as in 'Computers without Deployment Plug-in installed on Windows (x86)'
Default target might be deleted from policy.