Hi my friend, I have a better example on how karma is accumulative, and you don´t have to pay for one specific bad karma:
"After Jesus was crucified, the humanity haven’t enter the realm of God. If he suffered for us, the crucifixion was a penitence for our fault and sins, then it has failed, because the guilt continues, the sin continues, the suffering continues. So his suffering was in vain, then the crucifixion was not successful. Christianity has simply a myth. But the oriental analysis of the human life has a different attitude. Jesus crucifixion was the whole suffering accumulated from his past karmas. And this was his last life; he would not enter his earthly body again, so the suffering had to be crystallized, concentrated in a single spot. This single spot became the crucifixion.
He didn’t suffer for anyone else, nobody can suffer for nobody else. He suffered for himself, for his past karmas Nobody can set you free, because you are in a “prison” due to your own karmas; so how can Jesus liberate you? He can become a slave, he can become a free man, he can obtain liberation. Through crucifixion, he locked the account of his own karmas. It’s over, the chain has come to its end. The cause and effect had come to its end. This body won’t be born again; he will not enter in another uterus. If he would not have been an enlightened person, he would have to suffer this in many lifes. But he concentrated in a spot, in a single life.
You can’t interfere, if you interfere, you will only create more suffering for yourself. Do not interfere with the karmas, go beyond them, be a witness of them. Consider them a dream, not real; watch them and be indifferent. Do not get involved. Your body suffers: watch the suffering. Your body is happy: watch the happiness. Do not identify, that is what meditation means."
Acharya Rajneesh