Just because there are “pending kamma vipaka” does not mean all of them will actually bring vipaka. This is a very important point to remember.
We all may have done very bad kamma in previous lives and such vipaka MAY bear fruit in this life or in future lives.
However, we can REMOVE THE CONDITIONS that are necessary to bring those vipaka to materialize.
– One obvious way is to attain magga phala. If one attains the Sotapanna stage, for example, all previous kamma that are eligible to bring rebirths in the apayas will be INEFFECTIVE.
Even though Angulimala killed almost a thousand people, he was able to attain the Arahant stage. There are many lessons to be learned from that; see, “Account of Angulimāla – Many Insights to Buddha Dhamma“.
On the other hand, some kamma vipaka can bring vipaka, even for a Buddha (while still living).
But we can act with mindfulness and do our best NOT TO create suitable CONDITIONS for kamma vipaka to materialize; see, “What is Kamma? – Is Everything Determined by Kamma?“.
– One example that I always give is: If one goes to a bad neighborhood at night time, that is likely to bring some bad vipaka that is waiting for the right conditions to bear fruit.
– This is why being mindful of one’s actions is important, even in mundane matters.
– Another example is starting a long trip without making the necessary preparations. Planning is a necessary step in most cases.
You wrote, “I know establishing them in right view would be one of the best things. It’s been ineffective so far, but if I find sufficient evidence I may be able to do so.
I also transfer merits to them every day and practice metta towards them…”.
– So, you are doing what can be done to minimize the effects of such vipaka. Sincerely asking for forgiveness (during meditation sessions) is another thing that can be done. I do that every day. It is possible that we offend other people even without realizing it or even when we act with (what we think to be) good intentions.