Hi Mike,
You should create a weekly schedule with daily and hourly events.Where the daily events would be like daily @ 8PM and hourly events with once every 4 hours. Accordingly you must also set the retention schedules in the policy.Attached is a sample of the same.
Copy the exisiting policy under NMC->ManageData->Policies->Protection->Schedules->"Daily at Midnight with Hourly"
Edit the copied policy
Go to the hourly events tab,Now change the Frequency in minutes to 240( once every four hours)
Similarly go to the daily events tab and change the time at which daily snaphost need to be created.In my case I am leaving it at default of 12.
Go to the General tab and re-name the scheudle if required and Click apply.
Now
Copy the exisiting policy under NMC->ManageData->Policies->Protection->Schedules->"Sunday at Midnight with daily and hourly"
Edit the copied policy
Go to Daily Events tab Click and daily schedule and select the above policy that we created from the drop down list.
Now go to the Weekly events and click the day on which you want to create your weekly snapshots and the time.
Now rename the policy and click on apply and ok.
Now select your policy, you would like to use and change the retention duration, and apply the above created schedules.
Regards
adai