Fact:

[HKEY_USERS] keep the user registry of all user who have a profile on the computer.

[HKEY_CURRENT_USER] keep the registry of the profile currently load. (So technially, a branch of [HKEY_USERS] )

Problem :

I need to upgrade a registry key on all the profile currently on the machine. That mean a problem that will update [HKEY_USERS\.DEFAULT] and all [HKEY_USERS\****] profile locally!

Solution :

???