I am trying to have a group of PCs in an OU have a longer screensaver timeout than the default domain policy for all users that log into these PCs. I am trying to utilize security groups but have been unsuccessful.

All computers are in the same OU - Production.
I want to change the screensaver timeout for conference room PCs to 60 minutes; there is already a group policy applied to the Production OU that sets it to 15 minutes.
I created a group policy where the (user) screensaver policy is set to 60 minutes and linked it (to process after the normal screensaver GPO) to a test OU that mimics the Production OU.
Loopback Processing is set to Merge.

In my testing scenarios, I want to be able to log into PC1 as User1 and User2 and have the screensaver timeout set to 60 minutes AND log into PC2 as User1 and User2 and have the screensaver timeout set to 15 minutes.

Option 1: Set the scope to one PC only - PC1, removed Authenticated Users. Not the desired result.
User1 logged on to PC1: Screensaver set to 15 minutes
User2 logged on to PC2: Screensaver set to 15 minutes
User1 logged on to PC2: Screensaver set to 15 minutes
User2 logged on to PC2: Screensaver set to 15 minutes

Option 2: Set the Scope to one PC -PC1 and one User - User1. Not the desired result.
User1 logged on to PC1: Screensaver set to 60 minutes
User2 logged on to PC2: Screensaver set to 15 minutes
User1 logged on to PC2: Screensaver set to 60 minutes
User2 logged on to PC2: Screensaver set to 15 minutes

Option 3: Set the Scope back to one PC - PC1 and no user, Added Authenticated Users to Advanced Delegation with Read permissions.
User1 logged on to PC1: Screensaver set to 15 minutes
User2 logged on to PC2: Screensaver set to 15 minutes
User1 logged on to PC2: Screensaver set to 15 minutes
User2 logged on to PC2: Screensaver set to 15 minutes

Can anyone tell me what needs to be set to achieve the desired result without creating a new OU?