All good comments. It is good to think deeply about these issues.
But it is also clear that we can make decisions only based on our current status of understanding. Thus it is essential to keep learning and gradually remove all our wrong views. All wrong views are removed only at the Arahant stage.
– The grandmother made bad decisions because her level of ignorance was high.
– In case 2, person A may inform person B without thinking clearly about the possible bad consequences. Sometimes it is better NOT to do anything.
That last statement applies to speech often. It is better NOT to say things EVEN IF true if that is not the right place to say it. See, “Right Speech – How to Avoid Accumulating Kamma.”
Furthermore, we must always be mindful of our actions and speech. But it is also CRITICAL to be mindful of our THOUGHTS. As we have been discussing in the recent posts on “Origin of Life,” it is in our thoughts (specifically in javana citta) that we create kammic energies.