I ran into an issue where a local group policy had settings that were not accessible or editable using the conventional Local Group Policy editor (gpedit.msc), causing unwanted settings to be re-applied each time the group policy was refreshed. After a bit of searching around on the internet, I found a Powershell module with the ability to add, edit and remove individual items directly from Registry.pol policy files.
The module PolicyFileEditor can be downloaded and installed easily through Powershell:
Install-Module -Name PolicyFileEditor
As with everything from PSGallery, you need to have NuGet installed and updated.
The module comes with examples on how to use it. It can also be viewed online here.