I understand the basic workings of a regulator. I'm just wondering how it handles certain scenarios.

We have two people as an example.
Bob who doesn't wear a regulator and Timmy does wear one.

Scenario A:
One day Timmy dies for good. If Bob starts wearing a regulator after that, will it remove Bob's memories of Timmy, or will he still remember Timmy while only forgetting the people who died after he started wearing it?

Scenario B:
This time Bob who doesn't use a regulator dies.
Would Timmy's Regulator make him forget Bob or is the regulator only able to register the deaths of other regulator users?

To sum up my questions.
Does the Regulator scan and remove all memoires of death no matter what? Or can it only remove memories from after the time its worn?
Can it remove the memories of anyone that dies from a user or does the dead person have to also have a regulator for it to register?